6th Social - Term 1 Exam 2024 - Original Question Paper | Krishnagiri District | English Medium

First Term - Summative Examination - 2024

6th Standard - SOCIAL SCIENCE | English Medium

Time: 2.00 Hrs. | Marks: 60

PART - I

(Marks: 20 x 1 = 20)

a) Answer all the questions.

1. What was the step taken by the early man to collect his food?

1. Trade
2. Hunting
3. Painting
4. Rearing of animals

Answer: b) Hunting

2. River Valleys are said to be the cradle of civilisation because

1. soil is very fertile
2. they experience good climate
3. they are useful for transportation
4. many civilisations flourished on river valleys

Answer: d) many civilisations flourished on river valleys

3. The centre of the solar system

1. Sun
2. Earth
3. Comets
4. Jupiter

Answer: a) Sun

4. Name the book/s is written by A.P.J. Abdul kalam

1. India 2020
2. Wings of fire
3. Ignited minds
4. all of these

Answer: d) all of these

b) Fill in the blanks.

5. Ashoka Chakra has ................ spokes.

Answer: 24

6. ................. were used to store grains.

Answer: Granaries

7. ................. is known as the city of temples.

Answer: Madurai / Kanchipuram

8. The largest Ocean is ................. .

Answer: Pacific Ocean

c) State true or false.

9. During the period of Ashoka, Buddhism spread across the country.

Answer: True

10. Goat was the first animal to be domesticated by humans.

Answer: True

11. Granaries were used to store grains.

Answer: True

12. The frozen continent is Australia.

Answer: False. (The frozen continent is Antarctica)

d) Match the following.

13. Citadel

- Fishery

14. The Mariana Trench

- Equality before law

15. Coastal areas

- Raised platform

16. Article (14)

- Pacific ocean

Correct Matches:

• 13. Citadel - Raised platform
• 14. The Mariana Trench - Pacific ocean
• 15. Coastal areas - Fishery
• 16. Article (14) - Equality before law

e) Circle the odd one and write.

17. Oxen, sheep, buffaloes, horses.

Answer: horses

18. Africa, Europe, Australia, Srilanka.

Answer: Srilanka (The others are continents)

f) Which of the statement(s) is / are true? and write the correct statement.

19. Statement: Goods were imported and exported from the city Poompuhar.
Reason: Bay of Bengal was suitable for trading with neighbouring countries.

1. Statement is correct, but reason is wrong
2. Statement and its reason are correct
3. Statement is wrong, but reason is correct
4. Both are wrong

Answer: b) Statement and its reason are correct

20. Statement I: Earth is called a watery planet.
Statement II: The rotation of the Earth causes season.

1. I is true; II is wrong
2. I is wrong; II is true
3. Both the statements are true
4. Statements I and II are wrong

Answer: a) I is true; II is wrong (Reason: Rotation of the Earth causes day and night, not seasons. Revolution causes seasons.)

PART - II

(Marks: 6 x 2 = 12)

Answer any six questions.

21. Name some tools used by early man to hunt animals?

Early humans used tools made of stones, wood, and bones. Examples include stone axes, scrapers, sharp-edged flints, wooden spears, and bone needles.

22. Why did humans move from place to place?

Early humans were nomadic and moved from place to place in search of food, water, and shelter. They followed the migration of animals they hunted and the seasonal availability of fruits and plants.

23. Make a list of baked and raw foods that we eat?

• Baked Foods: Bread, cakes, cookies, pizza, roasted chicken.
• Raw Foods: Fruits (apple, banana), vegetables (carrot, cucumber), salads, nuts.

24. Mention the ancient cities of Tamilnadu?

The ancient cities of Tamilnadu include Madurai, Kancheepuram, and Poompuhar (also known as Kaveripoompattinam).

25. Name the inner planets?

The inner planets, also called terrestrial planets, are Mercury, Venus, Earth, and Mars.

26. Which ocean is named after a country?

The Indian Ocean is named after our country, India.

27. Why is India called a subcontinent?

India is called a subcontinent because it is a vast landmass with distinct geographical features like mountains, plateaus, and rivers, and diverse cultures, making it appear as a continent, but smaller than one.

28. What is discrimination?

Discrimination is the unfair or negative treatment of a person or a group of people based on prejudice related to their caste, religion, gender, race, or language.

29. What are the articles that are discussing the equality in the Indian constitution?

Articles 14 to 18 of the Indian Constitution discuss equality. Specifically, Article 14 ensures equality before the law and Article 15 prohibits discrimination on grounds of religion, race, caste, sex or place of birth.

30. Write the names of three major festivals celebrated in India?

Three major festivals celebrated in India are Diwali (Festival of Lights), Eid (celebrated by Muslims), and Christmas (celebrating the birth of Jesus Christ).

PART - III

(Marks: 4 x 5 = 20)

Answer the following in detail.

31. What are the benefits of a Museum? (OR) Describe the ancient methods of hunting?

Benefits of a Museum:

• Preservation: Museums preserve historical artifacts, art, and cultural heritage for future generations.
• Education: They serve as educational institutions, providing valuable information about history, science, and culture.
• Research: They offer resources for scholars and researchers to study the past.
• Inspiration: Museums inspire curiosity, creativity, and a deeper understanding of human history and the natural world.
• Cultural Identity: They help in understanding and appreciating our own culture and the culture of others.

32. Indus civilisation is called urban civilisation. Give reasons? (OR) Write about the Kings who ruled Madurai?

Indus Civilisation as an Urban Civilisation: The Indus Valley Civilisation is considered an urban civilisation because of its advanced and sophisticated features:

• Well-planned Cities: Cities like Harappa and Mohenjo-Daro were built on a grid pattern with well-laid-out streets.
• Advanced Drainage System: They had a highly developed covered drainage system, indicating a high regard for hygiene and sanitation.
• Use of Baked Bricks: Uniform, well-baked bricks were used for construction, ensuring durability.
• Public Buildings: Large, impressive structures like the Great Bath in Mohenjo-Daro and Granaries suggest a well-organized society and administration.
• Trade and Commerce: They had a flourishing trade network, both within the civilization and with Mesopotamia.

33. Explain the characteristics of the various spheres of Earth? (OR) Plains are highly populated. Give reasons?

Characteristics of the Spheres of Earth: The Earth is composed of four major spheres:

• Lithosphere (Land): This is the solid, rocky outer part of the Earth. It consists of the crust and the upper mantle. It provides land for living and is the source of minerals.
• Hydrosphere (Water): This sphere comprises all water on Earth, including oceans, seas, rivers, lakes, groundwater, and glaciers. It covers about 71% of the Earth's surface and is essential for all life.
• Atmosphere (Air): This is the gaseous layer that surrounds the Earth. It is composed mainly of nitrogen and oxygen and protects life from harmful solar radiation.
• Biosphere (Life): This is the narrow zone where the lithosphere, hydrosphere, and atmosphere interact to support life. It includes all living organisms, from the smallest microbes to the largest animals.

34. "India is a land of diversity, yet we are all united" - Explain. (OR) Explain the solution to the removal of inequal and discrimation in Indian socity?

"India is a land of diversity, yet we are all united": This statement reflects the core principle of "Unity in Diversity" in India.

• Diversity: India is incredibly diverse in terms of geography (mountains, plains, deserts), languages (over 1600 spoken), religions (Hinduism, Islam, Christianity, Sikhism, etc.), cultures, traditions, and food habits.
• Unity: Despite these differences, Indians are united by:
  • A common Constitution that guarantees equal rights to all.
  • National symbols like the National Flag, Anthem, and Emblem.
  • A shared history of the freedom struggle.
  • National festivals and sporting events that bring people together.
  • A sense of national identity as "Indians".
  This unique blend of diversity and unity is the greatest strength of our nation.

PART - IV

(Marks: 2 x 4 = 8)

Map work. (Answer all)

35. a) On the given outline map of Tamilnadu. Mark the following places.

1. Madurai
2. Kancheepuram
3. Poompuhar
4. Arrikamedu

Note: Students are required to locate and mark these ancient cities/ports on an outline map of Tamil Nadu.

35. b) On the given outline map of the world. Mark the following continents and Oceans.

1. Pacific Ocean
2. Asia
3. Indian Ocean
4. Africa

Note: Students are required to locate and mark the specified continents and oceans on an outline map of the World.

© 2024. Question Paper and Solutions prepared for educational purposes.

6th Social Science - Term 1 Exam 2024 - Original Question Paper | Chengalpattu District | English Medium

6th Social Science First Term Exam Question Paper with Solutions 2024

COMMON FIRST TERM SUMMATIVE EXAMINATION - 2024 | STANDARD - VI SOCIAL SCIENCE

Part I: Choose the correct answer (10 x 1 = 10)

1. What was the step taken by the early man to collect his food?

b) Hunting

2. Tanzania is situated in the continent of ______.

b) Africa

3. Indus Civilisation belonged to ______.

d) Metal Age

4. Which City is not related to the Bay of Bengal?

d) Kancheepuram

5. Circle the odd one.

d) horses

6. The galaxy in which our Solar System is found ______.

c) Milky way

7. Which of the following oceans is the busiest ocean?

b) The Atlantic Ocean

8. Mawsynram, the land of highest rainfall is located in ______.

d) Meghalaya

9. 'Discovery of India' - a book was written by ______.

d) Jawaharlal Nehru

10. A.P.J. Abdul Kalam was conferred Bharat Ratna in the year ______.

a) 1997

Part II: Fill in the blanks (5 x 1 = 5)

11. ______ was the first animal tamed by old stone Age man.

Dog

12. Group of people form ______.

society

13. The word planet means ______.

wanderer

14. ______ is the mineral rich plateau in India.

Chota Nagpur Plateau

15. ______ was the independent India's first law minister.

Dr. B.R. Ambedkar

Part III: Match the following (4 x 1 = 4)

16. Mohenjo - Daro	-	Mound of dead
17. Red planet	-	Mars
18. Zoroastrianism	-	Religion
19. Article 17	-	Abolition of untouchability

Part IV: Answer the following (Any 8) (8 x 2 = 16)

20. Mention the places from where we got Pre-historic tools.

Places where pre-historic tools were found include:

• Athirampakkam, Pallavaram, Gudiyam cave in Tamil Nadu.
• Bhimbetka in Madhya Pradesh.
• Hunsgi valley in Karnataka.

21. Why did humans move from place to place?

Early humans moved from place to place for several reasons:

• In search of food and water.
• To follow the movement of herds of animals which they hunted.
• To find shelter in caves and protect themselves from wild animals and harsh weather.

22. What are the uses of metal?

Metals are used for:

• Making tools for agriculture and hunting.
• Creating weapons for defense.
• Crafting ornaments and jewellery.
• Making utensils for cooking and storage.

23. Mention the other names of Madurai.

Other names for Madurai are Koodal, Naanmadakoodal, Thirualavai, and Malligai Maanagar (City of Jasmine).

24. Name the inner Planets.

The inner planets are Mercury, Venus, Earth, and Mars. They are also known as Terrestrial planets.

25. What is a Continent?

A continent is a vast, continuous expanse of landmass, usually separated by large bodies of water (oceans). There are seven continents on Earth: Asia, Africa, North America, South America, Antarctica, Europe, and Australia.

26. Why is India called a Sub Continent?

India is called a subcontinent because it has distinct geographical features like mountains (Himalayas), plateaus, plains, and oceans that separate it from the rest of Asia. It also possesses a wide variety of cultures, languages, and climates, making it a large and distinct landmass.

27. What is discrimination?

Discrimination is the unfair or prejudicial treatment of different categories of people, especially on the grounds of race, age, gender, caste, or religion. It is the action taken based on prejudice.

28. What is the difference between Naalangadi and Allangadi?

In ancient Tamil cities like Madurai, 'Naalangadi' referred to the day market, which was active during the daytime. 'Allangadi' referred to the night market, where business continued after sunset.

29. Distinguish between an Ocean and a Sea.

Ocean: An ocean is a vast and continuous body of saltwater that covers about 71% of the Earth's surface. Oceans are the largest water bodies (e.g., Pacific Ocean).

Sea: A sea is a smaller body of saltwater that is often partially enclosed by land or is a part of an ocean (e.g., Arabian Sea).

30. List out some of the classical dances of India.

• Bharatanatyam - Tamil Nadu
• Kathak - North India
• Kathakali - Kerala
• Kuchipudi - Andhra Pradesh
• Odissi - Odisha
• Manipuri - Manipur

31. What are the articles that are discussing the equality in the Indian Constitution?

The Indian Constitution discusses equality in several articles, primarily:

• Article 14: Equality before law.
• Article 15: Prohibition of discrimination on grounds of religion, race, caste, sex or place of birth.
• Article 17: Abolition of Untouchability.

Part V: Answer in Detail (Any 4) (4 x 5 = 20)

32. Indus Civilisation is called Urban Civilisation. Give Reasons.

The Indus Valley Civilisation is rightly called an urban civilisation because of its remarkable town planning and advanced infrastructure. The key reasons are:

• Well-Planned Cities: Cities like Harappa and Mohenjo-Daro were built on a grid pattern, with streets cutting across each other at right angles.
• Advanced Drainage System: They had a sophisticated covered drainage system. Every house had drains that connected to the main street drains, which were covered with bricks or stone slabs.
• Use of Baked Bricks: They used high-quality, uniform-sized baked bricks for construction, which ensured the durability of buildings.
• Great Bath and Granaries: The presence of large public structures like the Great Bath in Mohenjo-Daro and massive granaries in Harappa indicates a high degree of social and administrative organisation.
• Division of the City: The cities were typically divided into two parts: a raised citadel for important public buildings and a lower town for residential areas.

33. Write a Paragraph about the City Poompuhar with special reference to trade.

Poompuhar, also known as Kaveripoompattinam, was one of the most significant ancient port cities of the Chola kingdom. Located at the mouth of the river Kaveri, it served as a bustling hub for maritime trade. The city's prosperity is elaborately described in Sangam literature, especially in epics like 'Silappathikaram' and 'Pattinappalai'.

Poompuhar had a thriving trade relationship with foreign countries, including Greece and Rome. Ships from various nations docked at its harbour, bringing in valuable goods and taking back local products. Horses were imported by sea, while goods like pepper, pearls, precious stones, and fine textiles (cotton and silk) were exported. The city had well-organised markets and warehouses to facilitate this trade. The presence of a lighthouse guided ships safely to its port. Poompuhar stands as a testament to the advanced trading capabilities and economic power of the ancient Tamil kingdoms.

34. Distinguish between inner and outer planets.

Feature	Inner Planets	Outer Planets
Names	Mercury, Venus, Earth, Mars	Jupiter, Saturn, Uranus, Neptune
Composition	Made of dense, rocky materials.	Made of gases like hydrogen and helium (Gas Giants).
Size	Smaller in size.	Much larger in size (Giants).
Distance from Sun	Closer to the Sun.	Far from the Sun.
Rings	Do not have rings.	All have rings.
Moons	Have few or no moons.	Have many moons.

35. Write about the importance of Oceans.

Oceans are vital for life on Earth and play a crucial role in the planet's systems. Their importance can be understood through the following points:

• Climate Regulation: Oceans absorb a significant amount of solar energy and distribute it around the globe through currents, regulating global weather and climate patterns.
• Source of Rain: Most of the rainfall on Earth originates from the evaporation of ocean water, making them the primary source of freshwater through the water cycle.
• Biodiversity: Oceans host a vast array of marine life, from microscopic plankton to the largest whales, supporting rich and complex ecosystems.
• Food Source: They are a major source of food for humans, providing fish, shellfish, and other seafood.
• Transportation and Trade: Oceans have been the primary medium for transportation and trade between continents for centuries, connecting economies and cultures.
• Oxygen Production: Marine plants, like phytoplankton, produce more than half of the oxygen in the Earth's atmosphere.

36. "India is a land of diversity, Yet we are all United". Explain.

The phrase "Unity in Diversity" perfectly describes India. India is a land of immense diversity, which is visible in its geography, culture, language, and religion.

Diversity in India:

• Cultural Diversity: India has numerous festivals (Diwali, Eid, Christmas, Guru Nanak Jayanti), different forms of classical and folk dances, and varied customs and traditions.
• Linguistic Diversity: There are 22 officially recognised languages, and over 1,600 dialects are spoken across the country.
• Religious Diversity: It is the birthplace of four major religions (Hinduism, Buddhism, Jainism, Sikhism) and is home to people following Islam, Christianity, and other faiths.
• Geographical Diversity: India has diverse landforms, from the Himalayan mountains in the north to the coastal plains in the south, and from the deserts in the west to the dense forests in the east.

Unity among Indians:

Despite these differences, a strong sense of unity binds all Indians. This unity is fostered by:

• A Single Constitution: All citizens are governed by the same set of laws and enjoy the same rights.
• National Symbols: The National Flag, National Anthem, and National Emblem invoke a feeling of patriotism and oneness.
• Shared History: The common experience of the freedom struggle against British rule created a strong bond among people from all regions and communities.
• Interdependence: People from different regions depend on each other economically and culturally, which promotes harmony.

Thus, India stands as a proud example of a nation where diverse cultures coexist peacefully, bonded by a common identity of being an Indian.

37. What are the causes of Prejudice?

Prejudice, which is a preconceived opinion or feeling that is not based on reason or actual experience, arises from several causes:

• Ignorance and Misinformation: Lack of correct information about a particular group of people can lead to negative assumptions and stereotypes.
• Stereotypes: Fixing a generalized image or idea about a particular group of people. When people act on these stereotypes, it leads to prejudice.
• Socialization: People often learn prejudiced attitudes from their family, peers, and society. If a community holds negative views about another group, children may grow up absorbing these views.
• Economic Factors: Competition for jobs, resources, and opportunities can lead to one group blaming another for their problems, fostering resentment and prejudice.
• Historical Conflicts: Past conflicts or wars between different groups can leave a legacy of bitterness and mistrust that fuels prejudice for generations.
• Fear of the 'Other': People can be fearful or suspicious of those who are different from them in terms of culture, religion, or appearance, leading to prejudice.

Part VI: Mark the following places in the outline map of India (5 x 1 = 5)

38. Locate the following on an Indian map:

1. Delhi: Located in Northern India, it is the National Capital Territory.
2. Lothal: An ancient port city of the Indus Valley Civilization, located in the state of Gujarat on the west coast.
3. Harappa: A major city of the Indus Valley Civilization, located in the Punjab province of modern-day Pakistan. (Note: This is outside the modern political map of India).
4. Chennai: The capital city of Tamil Nadu, located on the Coromandel Coast (southeast coast) of India.
5. Indian Ocean: The large body of water located to the south of the Indian peninsula.

6th Standard English First Term Exam Question Paper 2024 with Answer Key | Ramanathapuram District

Solutions

I. Choose the appropriate synonyms for the given words from the options given: (3 x 1 = 3)

1. decade

• a. period of five years
• b. period of ten years
• c. period of seven years
• d. period of three years

✅ Answer: b. period of ten years

2. rambling

• a. wandering
• b. stopping
• c. interesting
• d. continuing

✅ Answer: a. wandering

3. delicious

• a. neatly
• b. fatly
• c. tastely
• d. bravely

✅ Answer: c. tastely (tasty)

II. Choose the appropriate antonyms for the given words from the options given: (3 x 1 = 3)

4. Wonderful

• a. terrible
• b. flexible
• c. amicable
• d. painful

✅ Answer: a. terrible

5. constantly

• a. regularly
• b. weekly
• c. occasionally
• d. continuously

✅ Answer: c. occasionally

6. foreign

• a. distant
• b. for
• c. outer
• d. native

✅ Answer: d. native

III. Answer the following appropriately: (10 x 1 = 10)

Identify the correct homophones:

7. Turtles live their (whole/hole) life in the sea.

✅ Answer: Turtles live their whole life in the sea.

8. The predators follow the (scent/sent) of the turtles to eat their eggs.

✅ Answer: The predators follow the scent of the turtles to eat their eggs.

Underline the Subject and Predicate of the given sentences:

9. Turtles live in the sea.

✅ Answer: Turtles (Subject) live in the sea (Predicate).

10. The boy is going to school.

✅ Answer: The boy (Subject) is going to school (Predicate).

Find out the compound word for the following words:

11. Water - a. shine b. fall c. hill d. body

✅ Answer: b. fall (Waterfall)

12. Compound - a. garden b. house c. wall d. gate

✅ Answer: c. wall (Compound wall)

Identify the following sentences:

13. Go to the river bed.

✅ Answer: Imperative sentence.

14. I like to play hide and seek.

✅ Answer: Declarative sentence (Statement).

15. Where did he go yesterday?

✅ Answer: Interrogative sentence.

16. What a beautiful flower it is!

✅ Answer: Exclamatory sentence.

IV. Answer any three of the following questions shortly: (3 x 2 = 6)

17. When do the sea turtles lay their eggs?

✅ Answer: Sea turtles come ashore to lay their eggs at night.

18. Name the turtles found in Indian coastal waters.

✅ Answer: The turtles found in Indian coastal waters are the Olive Ridley, Hawksbill, Green Sea Turtle, Loggerhead, and Leatherback.

19. When did the garden become a happy place for the author?

✅ Answer: The garden became a happy place for the author when his grandfather joined him and they worked together.

20. Why did the author leave town?

✅ Answer: The author left town to go to a boarding school.

21. Who first brought these vegetables to India?

✅ Answer: The Portuguese first brought vegetables like potato, tomato, and chilli to India.

22. Who came to India from Portugal in search of peppers?

✅ Answer: Vasco da Gama came to India from Portugal in search of peppers.

V. Answer any one in a paragraph: (1 x 5 = 5)

23. Describe the sea turtle's life.

The life of a sea turtle is a fascinating journey. It begins as an egg buried in the sand on a beach. After hatching, the baby turtle, or hatchling, makes a dangerous journey to the sea, avoiding predators. They spend their entire lives in the ocean, migrating long distances between feeding grounds and nesting sites. Female turtles return to the same beach where they were born to lay their own eggs. They face many threats from predators and human activities, but they are resilient creatures of the sea.

VI. Quote from memory poem: (1 x 5 = 5)

26. First five lines from the poem 'Trees'.

The Banyan is the largest of trees.
The Peepal quivers in the breeze.
The Coconut grows up straight and tall.
The Neem tree’s fruits are very small.
The Tamarind gives us pleasant shade.

VII. Read the following lines and answer the questions that follow: (4 x 1 = 4)

My mother would say
Little boy Raj...
Go to Muthu's

27. Who is Raj?

✅ Answer: Raj is a little boy.

28. Where did Raj's mother send him?

✅ Answer: Raj's mother sent him to Muthu's.

How do the little crocodile
Improve the shining tail
And for the water of the Nile

29. Identify the rhyming words?

✅ Answer: The rhyming words are 'tail' and 'Nile'.

30. Write the rhyme scheme.

✅ Answer: The rhyme scheme for these lines is aa.

VIII. Answer anyone in a paragraph: (1 x 5 = 5)

31. What does the poet say about crocodile?

In the poem 'The Crocodile' by Lewis Carroll, the poet describes the crocodile's appearance and clever nature. He says the crocodile improves its shining tail and pours the water of the Nile on its scales to look attractive. It seems to grin cheerfully and neatly spreads its claws. The poet says the crocodile welcomes little fishes in with a gently smiling jaw, indicating its predatory and deceptive nature.

IX. Choose the correct option from the options given: (4 x 1 = 4)

34. The last incredible ingredient added to the soup ____

• a. potato
• b. carrot
• c. chicken
• d. peas

✅ Answer: a. potato

35. The traveller started the villages how to ____

• a. make up
• b. share
• c. play
• d. waste

✅ Answer: b. share

36. The animals worried because ____

• a. there was heavy rain
• b. the farmer began to choke the tree
• c. the farmer chased them away
• d. the trees became old

✅ Answer: d. the trees became old

37. The baby Hippo was named after the ____

• a. rescuer
• b. Tsunami
• c. storm
• d. wind

✅ Answer: a. rescuer

X. Identify the character or speaker: (4 x 1 = 4)

38. I have children.

✅ Speaker: The Woodcutter.

39. There is no food here.

✅ Speaker: The Traveller.

40. I promise that I will never cut this tree.

✅ Speaker: The Woodcutter.

41. Owen was taken to your wildlife sanctuary.

✅ Speaker: A villager or rescuer.

XI. Read the passage and answer the questions that follow: (5 x 1 = 5)

Owen was taken to a wildlife sanctuary. Everyone thought he could be well looked after there. But Owen was not happy at all. He was tired and very frightened. As soon as he reached the sanctuary, he saw the large greyish tortoise. It looked bit motherly. He ran to the creature and hid behind it. Just like a baby hippo would hide behind its mother. The animal he chose was 130 year old giant tortoise called Mzee. Mzee was very surprised by Owen. But he left Owen to cuddle close to him. Soon the two of them became friends.

42. Why was Owen taken to the wildlife sanctuary?

✅ Answer: Owen was taken to the wildlife sanctuary so that he could be well looked after.

43. Who is Mzee?

✅ Answer: Mzee is a 130-year-old giant tortoise.

44. Why did Owen hide behind?

✅ Answer: Owen hid behind the tortoise because he was tired and frightened, and the tortoise looked motherly.

45. How does look the greyish tortoise?

✅ Answer: The greyish tortoise looked a bit motherly.

46. Why was Owen not happy?

✅ Answer: Owen was not happy because he was tired and very frightened.

XII. Letter Writing (Any one of the following): (6 x 1 = 6)

47. Write a letter to your father asking him permission to join an excursion party.

12, Gandhi Street,
Ramanathapuram.
25th September, 2024.

My Dearest Father,

I hope this letter finds you in good health. I am writing to you with an exciting request. My school is organizing an educational excursion to Mahabalipuram for two days next month.

All my friends are going, and I am very eager to join them. The trip will be very educational as we will be visiting historical monuments. The total cost for the trip is Rs. 1500, which includes travel, food, and accommodation. Our teachers will be accompanying us, so our safety will be well taken care of.

I kindly request you to grant me permission to go on this excursion and to send me the required amount. I promise to be very careful and responsible.

Waiting for your positive reply.

With lots of love,
Your loving son/daughter,
(Your Name)

7th Science First Term Summative Exam 2024 Question Paper with Answers | Samacheer Kalvi | Ranipet District

7th Science - First Term Exam 2024 - Solutions

I. Choose the appropriate answer. (10x1=10)

1. SI unit of density is __________.

b) Kg/m³

2. Light year is the unit of __________.

a) distance

3. A particle is moving in a circular path of radius 'r'. The displacement after half a circle would be __________.

c) 2r (Displacement is the diameter of the circle).

4. The metal which is liquid at room temperature is __________.

c) mercury

5. The sub-atomic particle which revolves around the nucleus is __________.

c) electron

6. Vegetative propagation by leaves takes place in __________.

a) bryophyllum

7. Climbing roots are seen in __________.

c) Both of them (Both betel and black pepper are climbers with climbing roots).

8. Sleep is not only good for our body, but it is also good for, __________.

c) mind

9. Tobacco chewing causes __________.

b) periodontitis

10. Which of the following is an example for animation?

c) Vector communication (Refers to vector graphics, a fundamental technology for creating 2D animation).

II. Answer any 15 questions: (15x2=30)

11. Define - Astronomical unit.

An Astronomical Unit (AU) is defined as the mean distance between the center of the Earth and the center of the Sun. 1 AU ≈ 149.6 million kilometers.

12. Fill in the blanks

a) Density of mercury is 13,600 kg/m³.

b) One cubic metre is equal to 10,00,000 cubic centimetre.

13. Analogy.

a) Velocity : metre / Second :: Acceleration : metre / second² (m/s²)

b) Length of scale : metre :: Speed of aeroplane : Knot or km/h

14. Distinguish between speed and velocity.

• Speed: It is the rate of change of distance. It is a scalar quantity, having only magnitude.
• Velocity: It is the rate of change of displacement. It is a vector quantity, having both magnitude and direction.

15. What are compounds? Give two examples.

A compound is a pure substance formed when two or more elements are chemically combined in a fixed ratio by mass.
Examples: Water (H₂O), Carbon dioxide (CO₂).

16. Define the following terms with an example for each.

a) Element: A pure substance that consists of only one kind of atom. Ex: Iron (Fe).

b) Compound: A substance formed by the chemical combination of two or more elements. Ex: Sodium Chloride (NaCl).

c) Metal: An element that is typically hard, shiny, malleable and a good conductor of heat and electricity. Ex: Copper (Cu).

d) Non-metal: An element that is typically dull, brittle and a poor conductor of heat and electricity. Ex: Sulphur (S).

e) Metalloid: An element that has properties intermediate between metals and non-metals. Ex: Silicon (Si).

17. Match the following:

a) Valency - Electrons in the outermost orbit

b) Neutral particle - Neutron

c) Iron - Fe

d) Hydrogen - Monovalent

18. State true or False. If false, correct the Statement.
The nucleus is surrounded by protons.

False.
Correct Statement: The nucleus is surrounded by electrons.

19. Match the following:

a) Petal - Attracts insect

b) Fern - Spore

c) Hooks - Bignonia

d) Phylloclade - Opuntia

20. What is cross pollination?

Cross-pollination is the transfer of pollen grains from the anther of a flower to the stigma of a genetically different flower, i.e., a flower on another plant of the same species.

21. What are the two important parts of a flower?

The two important (essential) parts of a flower are the Androecium (male reproductive part) and the Gynoecium (female reproductive part).

22. Fill in the blanks:

a) I am green colour box with garbage. I am a green dustbin (for biodegradable waste).

b) Tuberculosis is caused by the bacterium Mycobacterium tuberculosis.

23. What is hygiene?

Hygiene refers to conditions and practices that help to maintain health and prevent the spread of diseases. It includes personal cleanliness and maintaining clean surroundings.

24. Name the mode of transmission of communicable diseases.

Communicable diseases are transmitted through:

• Direct contact
• Air (droplet infection)
• Contaminated food and water
• Vectors (insects like mosquitoes)

25. Define: Mastication

Mastication is the process of chewing food with the teeth in the mouth. It breaks down food into smaller particles and mixes it with saliva to begin digestion.

26. Write a note on 2D and 3D pictures.

2D (Two-Dimensional) pictures: These have only two dimensions: length and width. They appear flat. Examples: Drawings on paper, photographs.
3D (Three-Dimensional) pictures: These have three dimensions: length, width, and depth. They create an illusion of depth and look realistic. Examples: Sculptures, 3D movies.

27. Differentiate mass number from atomic number.

Atomic Number (Z): It is the number of protons present in the nucleus of an atom. It is unique for each element.
Mass Number (A): It is the total number of protons and neutrons present in the nucleus of an atom.

28. Define, molecule.

A molecule is the smallest particle of an element or a compound that can exist independently and shows all the properties of that substance. It consists of two or more atoms chemically bonded together.

29. What is Centre of gravity?

The center of gravity of an object is the point through which the entire weight of the object appears to act, regardless of the object's orientation.

30. Define Stability.

Stability is the ability of an object to maintain its original position. An object is stable if its center of gravity is as low as possible.

III. Answer all the questions (4x5=20)

31. a) How will you determine the density of a stone using a measuring Jar?

1. Measure the mass: First, find the mass (m) of the stone using a physical balance. Let the mass be 'm' grams.
2. Measure the initial volume: Take a measuring jar and pour some water into it. Note the initial volume of the water (V₁).
3. Immerse the stone: Tie the stone with a thread and gently lower it into the measuring jar until it is fully submerged.
4. Measure the final volume: The water level will rise. Note the final volume of the water with the stone in it (V₂).
5. Calculate the volume of the stone: The volume of the stone is the difference between the final and initial readings. Volume (V) = V₂ - V₁.
6. Calculate the density: Use the formula for density:
   Density (ρ) = Mass (m) / Volume (V). The unit will be g/cm³.

(or)

b) Explain the types of Stability with suitable examples?

There are three types of stability:

1. Stable Equilibrium: An object is in stable equilibrium if it returns to its original position after being slightly displaced. In this state, the center of gravity is at its lowest possible position. When displaced, the center of gravity is raised.
   Example: A cone resting on its base.
2. Unstable Equilibrium: An object is in unstable equilibrium if it does not return to its original position after being slightly displaced and instead topples over. In this state, the center of gravity is at its highest position. When displaced, the center of gravity is lowered.
   Example: A cone balanced on its vertex (tip).
3. Neutral Equilibrium: An object is in neutral equilibrium if it remains in the new position after being displaced. The height of its center of gravity remains constant.
   Example: A ball rolling on a horizontal surface.

32. a) Differentiate metals and non-metals?

Property	Metals	Non-metals
State	Usually solid at room temperature (except Mercury).	Exist as solids, liquids, or gases.
Lustre	Have a shiny surface (lustrous).	Have a dull surface (non-lustrous).
Malleability	Can be beaten into thin sheets (malleable).	Brittle and break when hammered.
Ductility	Can be drawn into wires (ductile).	Cannot be drawn into wires (non-ductile).
Conductivity	Good conductors of heat and electricity.	Poor conductors of heat and electricity (except graphite).
Examples	Iron, Copper, Gold	Sulphur, Oxygen, Carbon

(or)

b) Draw the structure of an atom and explain the position of the sub-atomic particles.

An atom consists of a central nucleus and electrons that orbit the nucleus. The positions of the sub-atomic particles are:

• Protons: They are positively charged particles located inside the nucleus at the center of the atom.
• Neutrons: They are neutral particles (no charge) also located inside the nucleus along with the protons.
• Electrons: They are negatively charged particles that revolve around the nucleus in specific, fixed paths called orbits or shells.

33. a) Explain the underground stems.

Underground stems are modified stems that grow below the surface of the soil. They are adapted for food storage and vegetative propagation.
Types of Underground Stems:

• Rhizome: It is a thick, horizontal stem that grows beneath the soil. It has nodes, internodes, and scale leaves. Example: Ginger, Turmeric.
• Tuber: It is the swollen, fleshy tip of an underground stem branch. It stores food as starch and has buds called 'eyes'. Example: Potato.
• Bulb: It is a condensed underground stem with a terminal bud and fleshy scale leaves that store food. Example: Onion, Garlic.
• Corm: It is a short, swollen, upright, underground stem that stores food. It has a solid, fleshy structure. Example: Colocasia.

(or)

b) Write a brief account on Pollination.

Pollination is the process of transferring pollen grains from the anther (male part) to the stigma (female part) of a flower.

Types of Pollination:

1. Self-Pollination (Autogamy): The transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant.
2. Cross-Pollination (Allogamy): The transfer of pollen grains from the anther of a flower on one plant to the stigma of a flower on another plant of the same species.

Agents of Pollination:

Pollination is carried out by various agents, which can be biotic (living) or abiotic (non-living).

• Abiotic agents: Wind (Anemophily), Water (Hydrophily).
• Biotic agents: Insects (Entomophily), Birds (Ornithophily), Bats (Chiropterophily).

34. a) Write about any three communicable disease?

Three communicable diseases are:

1. Tuberculosis (TB): It is an infectious disease caused by the bacterium *Mycobacterium tuberculosis*. It primarily affects the lungs. It spreads through the air when an infected person coughs or sneezes. Symptoms include a persistent cough, fever, and weight loss.
2. Cholera: It is an acute diarrhoeal disease caused by the bacterium *Vibrio cholerae*. It spreads through contaminated food and water. It leads to severe dehydration and can be fatal if not treated promptly.
3. Common Cold: It is a viral infectious disease of the upper respiratory tract. It is caused by rhinoviruses and spreads through airborne droplets or direct contact with infected objects. Symptoms include a runny nose, sneezing, and sore throat.

(or)

b) How the diseases are transmitted from person to the other person?

Diseases can be transmitted from one person to another through several modes:

• Direct Contact: Transmission through physical contact with an infected person, such as touching or kissing. E.g., Chickenpox.
• Indirect Contact: Transmission through contact with contaminated objects (fomites) used by an infected person, like utensils, clothes, or doorknobs.
• Through Air (Droplet Infection): Pathogens are spread through droplets released into the air when an infected person coughs, sneezes, or talks. E.g., Common Cold, Tuberculosis.
• Through Contaminated Food and Water: Consuming food or water that has been contaminated with pathogens. E.g., Cholera, Typhoid.
• Through Vectors: Organisms like mosquitoes, flies, and ticks can carry pathogens from an infected person to a healthy person. E.g., Malaria is transmitted by mosquitoes.

10th Science - Quarterly Exam 2024 - Original Question Paper with Solutions | Chengalpattu District

Solutions

Part - I (12 x 1 = 12)

Choose the correct answer and write it with the option code.

1. Impulse is equal to
   • rate of change of momentum
   • rate of force and time
   • change of momentum
   • rate of change of mass
   c) change of momentum
2. The eye defect "presbyopia" can be corrected by
   • Convex lens
   • Concave lens
   • Convex mirror
   • Bifocal lenses
   d) Bifocal lenses
3. The value of universal gas constant
   • 3.81 Jmol⁻¹K⁻¹
   • 8.03 Jmol⁻¹K⁻¹
   • 1.38 Jmol⁻¹K⁻¹
   • 8.31 Jmol⁻¹K⁻¹
   d) 8.31 Jmol⁻¹K⁻¹
4. SI unit of resistance is
   • Ohm
   • Joule
   • mho
   • ohm meter
   a) Ohm
5. Which of the following represents 1 amu?
   • Mass of a C-12 atom
   • Mass of a hydrogen atom
   • 1/12th of the mass of a C-12 atom
   • Mass of O-16 atom
   c) 1/12th of the mass of a C-12 atom
6. What is the formula of Blue vitriol?
   • CuSO₄·xH₂O
   • CaSO₄·2H₂O
   • FeSO₄·7H₂O
   • CuSO₄·5H₂O
   d) CuSO₄·5H₂O
7. The process of coating the surface of metal with a thin layer of zinc is called
   • painting
   • thinning
   • galvanization
   • electroplating
   c) galvanization
8. Kreb's cycle takes place in
   • chloroplast
   • mitochondrial matrix
   • stomata
   • inner mitochondrial membrane
   b) mitochondrial matrix
9. The segments of leech are known as
   • metameres
   • proglottids
   • strobila
   • All the above
   a) metameres
10. Which of the correct sequence of blood flow
    • Ventricle → atrium → Vein → arteries
    • atrium → Ventricle → Vein → arteries
    • atrium → Ventricle → arteries → Vein
    • Ventricles → Vein → atrium → arteries
    c) atrium → Ventricle → arteries → Vein (Note: This is a simplified representation. Arteries branch into capillaries, which then converge into veins that return blood to the atrium).
11. Which hormone is secreted by the thymus gland?
    • oxytocin
    • Thymosin
    • pineal gland
    • Thyroxin
    b) Thymosin
12. The _______ units form the backbone of the DNA.
    • 5 carbon sugar
    • phosphate
    • Nitrogenous base
    • Sugar phosphate
    d) Sugar phosphate

Part - II (7 x 2 = 14)

Answer any 7 questions. (Q.No. 22 is compulsory)

13. State Newton's second law.
    Newton's second law of motion states that the rate of change of momentum of a body is directly proportional to the applied external force and takes place in the direction of the force. Mathematically, F ∝ Δp/t, which leads to the equation F = ma (Force = mass × acceleration).
14. Distinguish between ideal gas and real gas.

    Ideal Gas	Real Gas
    The intermolecular force of attraction is zero.	The intermolecular force of attraction is not zero.
    The volume of the molecules is negligible compared to the volume of the gas.	The volume of the molecules is not negligible.
    Obeys the ideal gas equation (PV=nRT) at all temperatures and pressures.	Obeys the ideal gas equation only at high temperatures and low pressures.

15. What is rust? Give the equation for formation of rust.
    Rust is hydrated ferric oxide (Fe₂O₃·xH₂O), a reddish-brown substance formed when iron corrodes by reacting with oxygen and water.
    Equation: 4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O (Rust)
16. Classify the following substances into deliquescent and hygroscopic: Con sulphuric acid, Copper sulphate pentahydrate, Silica gel, Calcium chloride and Gypsum salt.
    Deliquescent: Calcium chloride
    Hygroscopic: Concentrated sulphuric acid, Copper sulphate pentahydrate, Silica gel, Gypsum salt.
17. Write the reaction for photosynthesis.
    The balanced chemical equation for photosynthesis is:
    6CO₂ (Carbon dioxide) + 6H₂O (Water) →(in presence of Sunlight & Chlorophyll) C₆H₁₂O₆ (Glucose) + 6O₂ (Oxygen)
18. a) Give the common name of the Hirudinaria granulosa. b) What does CNS stand for?
    a) The common name of Hirudinaria granulosa is the Indian cattle leech.
    b) CNS stands for Central Nervous System.
19. Draw and label the diagram.
    The diagram in the question paper depicts Guard cell in turgid condition.

    

    Guard cells (swollen):
    Stoma
20. What is bolting? How can it be induced artificially?
    Bolting is the premature or elongated growth of an internodal stem just before flowering in plants that typically have a rosette-like growth habit (e.g., cabbage, beet).
    Artificial Induction: It can be induced artificially by the application of plant hormones like Gibberellins.
21. What do you understand by the term phenotype and genotype?
    Phenotype: The phenotype refers to the observable physical and biochemical characteristics of an organism, such as height, flower color, or blood type. It is determined by both the genotype and environmental factors.
    Genotype: The genotype is the genetic constitution or makeup of an organism, representing the set of genes it carries.
22. The work done in moving a charge of 10C across two points in a circuit is 100J. What is the potential difference between the points?
    Given:

    • Work done (W) = 100 J
    • Charge (Q) = 10 C

    The formula for potential difference (V) is V = W / Q.
    V = 100 J / 10 C
    V = 10 Volts (V)
    The potential difference between the points is 10 V.

Part - III (7 x 4 = 28)

Answer any 7 questions. (Q.No. 32 is compulsory)

23. Define inertia. Give its classification.
    Inertia: The inherent property of a body to resist any change in its state of rest or state of uniform motion, unless it is influenced by an external unbalanced force.
    
    Classification: Inertia is classified into three types:

    1. Inertia of Rest: The resistance of a body to change its state of rest. (e.g., A passenger jerks backward when a bus suddenly starts).
    2. Inertia of Motion: The resistance of a body to change its state of uniform motion. (e.g., An athlete runs a certain distance before a long jump to maintain motion).
    3. Inertia of Direction: The resistance of a body to change its direction of motion. (e.g., Passengers are pushed sideways when a bus takes a sharp turn).
24. a) List any 2 properties of light. b) Why does the sky appear in blue colour?
    a) Properties of light:

    1. Rectilinear Propagation: Light travels in a straight line in a homogenous medium.
    2. Reflection: Light bounces back when it strikes a polished surface.
    3. Refraction: Light bends when it travels from one medium to another.
    4. Scattering: Light is deflected in various directions by particles in its path.

    b) Why the sky appears blue: The sky appears blue due to a phenomenon called Rayleigh scattering. When sunlight enters the Earth's atmosphere, the tiny molecules of air (like nitrogen and oxygen) scatter the sunlight. Blue light, having a shorter wavelength, is scattered much more effectively than red light (which has a longer wavelength). As we look at the sky, this scattered blue light reaches our eyes from all directions, making the sky appear blue.
25. Match the items in column I to the items in column II.

    Column I	Column II	Correct Match
    i) electric current	volt	i) → ampere ii) → volt iii) → ohm meter iv) → watt
    ii) potential difference	ohm meter
    iii) specific resistance	watt
    iv) electric power	ampere

26. a) What happens when MgSO₄·7H₂O is heated? Write the appropriate equation. b) Define Solubility.
    a) Heating of MgSO₄·7H₂O: When Magnesium sulphate heptahydrate (Epsom salt) is heated, it loses its water of crystallization and becomes anhydrous magnesium sulphate, a white crystalline solid.
    Equation: MgSO₄·7H₂O(s) →(Heat) MgSO₄(s) + 7H₂O(g)
    
    b) Solubility: Solubility is defined as the maximum amount of a solute (in grams) that can be dissolved in 100 grams of a solvent to form a saturated solution at a specific temperature.
27. Fill in the blanks and answer the Assertion/Reason question.
    Fill in the blanks:
    a) Atomic number forms the basis of the modern periodic table.
    b) The chief ore of Aluminium is Bauxite (Al₂O₃·2H₂O).
    
    Assertion and Reason:
    c) Assertion: Magnesium is used to protect steel from rusting.
    Reason: Magnesium is more reactive than iron.
    Answer: i) A and R are correct. R explains the A. (Magnesium acts as a sacrificial anode because it is more reactive and corrodes preferentially, thereby protecting the steel).
28. Differentiate the following: aerobic and anaerobic respiration.

    Feature	Aerobic Respiration	Anaerobic Respiration
    Oxygen Requirement	Occurs in the presence of oxygen.	Occurs in the absence of oxygen.
    Location	Cytoplasm and Mitochondria.	Only in the Cytoplasm.
    Breakdown of Glucose	Complete oxidation.	Incomplete oxidation.
    End Products	Carbon dioxide (CO₂), Water (H₂O).	Ethanol and CO₂ (in yeast) or Lactic acid (in muscles).
    Energy Yield	High (approx. 36-38 ATP molecules).	Low (only 2 ATP molecules).

29. List out the parasitic adaptations in leech.
    Parasitic adaptations of leech (Hirudinaria) include:

    • Suckers: Possesses anterior and posterior suckers for strong attachment to the host.
    • Pharynx: A muscular pharynx is present for sucking blood from the host.
    • Anticoagulant: The saliva contains hirudin, which prevents the clotting of blood, ensuring a continuous supply.
    • Alimentary Canal: The crop is large and can store a large amount of blood, which is digested slowly.
    • Anaerobic Respiration: Can respire anaerobically, which is useful when it is attached to a host.
30. State whether true or false. a) The phloem is responsible for the translocation of food. b) When guard cells lose water the stomata opens. c) Bring out any two physiological activities of abscisic acid.
    a) True. Phloem transports sugars (food) from the leaves to other parts of the plant.
    b) False. When guard cells lose water, they become flaccid, and the stomata close.
    c) Two physiological activities of abscisic acid (ABA):

    1. Promotes Dormancy: It induces dormancy in buds and seeds, helping them survive unfavourable conditions.
    2. Stress Hormone: It causes the closure of stomata during water stress (drought) to reduce water loss through transpiration.
31. Enumerate the functions of blood.
    The main functions of blood are:

    • Transport: It transports respiratory gases (O₂ and CO₂), digested food (nutrients), hormones, enzymes, and waste products (like urea).
    • Regulation: It helps in regulating body temperature, pH (acid-base balance), and water balance.
    • Protection: It protects the body from disease-causing pathogens through white blood cells (WBCs) and antibodies. It also prevents excessive blood loss through the process of clotting (platelets and clotting factors).
32. a) Identify the bond between H and F in HF molecule. b) What property forms the basis of Identification? c) How does the property vary in periods and in groups?
    a) The bond between Hydrogen (H) and Fluorine (F) in an HF molecule is a polar covalent bond.
    
    b) The property that forms the basis for this identification is the difference in electronegativity between the two atoms. Fluorine is the most electronegative element, while hydrogen has a much lower electronegativity, leading to unequal sharing of electrons.
    
    c) Variation of Electronegativity:

    • Across a Period (left to right): Electronegativity generally increases due to an increase in nuclear charge and a decrease in atomic size.
    • Down a Group (top to bottom): Electronegativity generally decreases due to an increase in atomic size and shielding effect, which reduces the attraction of the nucleus for the bonding electrons.

Part - IV (3 x 7 = 21)

Answer in detail.

33. What are the types of inertia? Give an example for each.
    [Answered in Part III, Question 23. This is a detailed version.]
    
    Inertia is the inherent property of a body to resist any change in its state of rest or uniform motion unless acted upon by an external force.
    
    There are three types of inertia:

    1. Inertia of Rest

    It is the inability of a body to change its state of rest by itself.

    Example: When you vigorously shake the branches of a tree, some of the leaves and fruits get detached and fall down. This is because the branches come into motion while the leaves and fruits tend to remain at rest due to inertia of rest. This causes them to detach.

    2. Inertia of Motion

    It is the inability of a body to change its state of uniform motion by itself.

    Example: When a bus is moving, a passenger inside also moves along with it. If the driver applies the brakes suddenly, the bus comes to a stop, but the passenger's body continues to move forward due to inertia of motion. This is why passengers are jerked forward when a moving bus stops.

    3. Inertia of Direction

    It is the inability of a body to change its direction of motion by itself.

    Example: When a car moving in a straight line takes a sharp turn to the right, the passengers are pushed towards the left. This is because the car changes its direction, but the passengers' bodies tend to continue moving in the original straight-line direction due to inertia of direction.

    [OR]

    Derive the ideal gas equation.

    The ideal gas equation is an equation of state for a hypothetical ideal gas. It is derived by combining three empirical gas laws:
    
    1. Boyle's Law: At constant temperature (T) and number of moles (n), the volume (V) of a gas is inversely proportional to its pressure (P).

    V ∝ 1/P .......... (1)

    2. Charles's Law: At constant pressure (P) and number of moles (n), the volume (V) of a gas is directly proportional to its absolute temperature (T).

    V ∝ T .......... (2)

    3. Avogadro's Law: At constant temperature (T) and pressure (P), the volume (V) of a gas is directly proportional to the number of moles (n).

    V ∝ n .......... (3)

    Combining the three laws: By combining equations (1), (2), and (3), we get:

    V ∝ nT/P

    This can be written as:

    V = R (nT/P)

    where R is a constant of proportionality called the Universal Gas Constant. Rearranging the equation, we get the ideal gas equation:

    PV = nRT

    The value of R is constant for all gases and is approximately 8.314 J mol⁻¹ K⁻¹.
34. a) Give the salient features of "Modern atomic theory". [5 marks] b) Calculate the molecular mass of CO₂. [2 marks]

    a) Salient Features of Modern Atomic Theory

    1. Atom is no longer indivisible: An atom is composed of subatomic particles like protons, neutrons, and electrons.
    2. Atoms of the same element may not be identical: The existence of isotopes (e.g., ¹H, ²H, ³H) proves that atoms of the same element can have different mass numbers.
    3. Atoms of different elements may be identical: The existence of isobars (e.g., ⁴⁰Ar, ⁴⁰K, ⁴⁰Ca) proves that atoms of different elements can have the same mass number.
    4. Atom is the smallest particle in a chemical reaction: The atom is the smallest unit of matter that takes part in a chemical reaction.
    5. Mass can be converted into energy: The mass of an atom can be converted into energy according to Einstein's equation, E = mc². This is not conserved separately in nuclear reactions.
    6. The ratio of atoms in a molecule may not be simple: Atoms may combine in a ratio that is not simple whole numbers, as seen in complex organic molecules like sucrose (C₁₂H₂₂O₁₁).

    b) Calculation of molecular mass of CO₂

    To calculate the molecular mass of Carbon Dioxide (CO₂), we need the atomic masses of Carbon (C) and Oxygen (O).

    • Atomic mass of Carbon (C) ≈ 12.01 u
    • Atomic mass of Oxygen (O) ≈ 16.00 u

    The formula for CO₂ indicates one Carbon atom and two Oxygen atoms.

    Molecular Mass of CO₂ = (1 × Atomic mass of C) + (2 × Atomic mass of O)

    = (1 × 12.01) + (2 × 16.00)

    = 12.01 + 32.00

    = 44.01 u (or g/mol for molar mass)

    [OR]

    Write a note on Various factors affecting solubility.

    Solubility is the ability of a solute to dissolve in a solvent. It is affected by several factors:

    1. Nature of the Solute and Solvent

    This is governed by the principle "like dissolves like".

    • Polar solutes (like salt, NaCl) tend to dissolve in polar solvents (like water, H₂O).
    • Non-polar solutes (like grease, oil) tend to dissolve in non-polar solvents (like ether, CCl₄).

    2. Temperature

    The effect of temperature depends on the state of the solute and solvent.

    • Solids in Liquids: For most solid solutes, solubility increases as the temperature increases (e.g., dissolving sugar in hot water). However, for some substances like cerium sulfate (Ce₂(SO₄)₃), solubility decreases with an increase in temperature.
    • Gases in Liquids: The solubility of gases in liquids decreases as the temperature increases. This is why boiled water has a "flat" taste, as dissolved gases like oxygen have escaped.

    3. Pressure

    • Solids and Liquids: A change in pressure has a negligible effect on the solubility of solid and liquid solutes.
    • Gases in Liquids: The solubility of a gas in a liquid is directly proportional to the pressure of the gas over the liquid. This is stated by Henry's Law. For example, carbonated drinks are bottled under high pressure to increase the solubility of CO₂ gas in the liquid.
35. With a neat labelled diagram explain the structure of a neuron.
    [Image of a Neuron]
    A diagram showing the main parts: Dendrites, Cell Body (Cyton) with a Nucleus, Axon, Myelin Sheath, Nodes of Ranvier, and Axon Terminals.

    A neuron (or nerve cell) is the structural and functional unit of the nervous system. It consists of three main parts:

    1. Cell Body (Cyton or Soma)

    • It is the main part of the neuron, with a large, central nucleus and cytoplasm.
    • The cytoplasm contains characteristic, deeply stained particles called Nissl's granules, which are involved in protein synthesis.
    • It controls all the metabolic activities of the neuron.

    2. Dendrites

    • These are short, branched cytoplasmic extensions that arise from the cell body.
    • They receive nerve impulses from other neurons or sensory receptors and transmit them towards the cell body.

    3. Axon

    • It is a single, long, slender projection that arises from the cell body.
    • It is responsible for carrying nerve impulses away from the cell body to other neurons or to effector organs (muscles or glands).
    • The axon is often covered by a protective sheath called the myelin sheath, which is made of Schwann cells. The myelin sheath acts as an insulator and speeds up the transmission of nerve impulses.
    • The myelin sheath is not continuous; it has gaps called the Nodes of Ranvier, where the nerve impulse "jumps" from one node to the next (saltatory conduction).
    • The end of the axon branches into fine filaments called axon terminals, which end in synaptic knobs. These knobs release neurotransmitters to transmit the signal to the next neuron.

    [OR]

    With a neat labelled diagram describe the parts of a typical angiospermic ovule.

    [Image of an Anatropous Ovule]
    A diagram showing the ovule attached to the ovary wall, with labels for Funiculus, Hilum, Integuments (outer and inner), Micropyle, Chalaza, Nucellus, and Embryo sac containing the egg cell, synergids, polar nuclei, and antipodal cells.

    An ovule is the structure within the ovary of a flowering plant that contains the female reproductive cell and, after fertilization, develops into a seed. A typical anatropous ovule consists of the following parts:

    • Funiculus (or Funicle): The stalk that attaches the ovule to the placenta in the ovary wall.
    • Hilum: The point of attachment where the body of the ovule fuses with the funiculus.
    • Integuments: One or two protective layers that surround the main body of the ovule, leaving a small opening. After fertilization, they develop into the seed coat.
    • Micropyle: A small opening at the apex of the integuments through which the pollen tube usually enters the ovule for fertilization.
    • Chalaza: The basal part of the ovule, opposite the micropyle, where the nucellus and integuments originate.
    • Nucellus: A mass of parenchymatous tissue that encloses the embryo sac. It provides nourishment to the developing embryo sac.
    • Embryo Sac (Female Gametophyte): A large, oval cell located within the nucellus that contains the female gamete. A mature embryo sac typically contains:
      • Egg Apparatus: Located at the micropylar end, it consists of one egg cell and two flanking synergids.
      • Antipodal Cells: Three cells located at the chalazal end.
      • Central Cell: The large central cell containing two polar nuclei, which fuse to form the secondary nucleus before fertilization.