7th Science - First Term Exam Paper 2024 with Solutions
Examination: COMMON FIRST TERM SUMMATIVE EXAMINATION - 2024
Standard: VII
Subject: SCIENCE
Time: 2.00 hrs
Marks: 60
I. Choose the appropriate answer. 10x1=10
1. SI unit of density is __________
2. Light year is the unit of __________
3. A particle is moving in a circular path of radius 'r'. The displacement after half a circle would be __________
4. The metal which is liquid at room temperature is __________
5. The sub-atomic particle which revolves around the nucleus is __________
6. Vegetative propagation by leaves takes place in __________
7. Climbing roots are seen in __________
8. Sleep is not only good for our body, but it is also good for __________
9. Tobacco chewing causes __________
10. Which of the following is an example for animation?
II. Answer any 15 questions. 15x2=30
11. Define - Astronomical unit.
12. Fill in the blanks
a) Density of mercury is 13600 kg/m³.
b) One cubic metre is equal to 10,00,000 cubic centimetre.
13. Analogy.
a) Velocity : metre / Second :: Acceleration : metre / Second²
b) Length of scale : metre :: Speed of aeroplane : Knot
14. Distinguish between speed and velocity.
Speed: It is the rate of change of distance. It is a scalar quantity, meaning it only has magnitude.
Velocity: It is the rate of change of displacement. It is a vector quantity, meaning it has both magnitude and direction.
15. What are compounds? Give two examples.
A compound is a substance formed when two or more chemical elements are chemically bonded together.
Examples: Water (H₂O), Carbon Dioxide (CO₂).
16. Define the following terms with an example for each.
- a) Element: A pure substance consisting only of atoms that all have the same number of protons. Ex: Oxygen (O).
- b) Compound: A substance formed from two or more elements chemically united in fixed proportions. Ex: Salt (NaCl).
- c) Metal: An element that is typically shiny, malleable, and a good conductor of heat and electricity. Ex: Iron (Fe).
- d) Non-metal: An element that lacks the characteristics of a metal. Ex: Sulphur (S).
- e) Metalloid: An element with 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?
21. What are the two important parts of a flower?
22. Fill in the blanks:
a) I am green colour box with garbage. I am a biodegradable waste bin.
b) Tuberculosis is caused by the bacterium Mycobacterium tuberculosis.
23. What is hygiene?
24. Name the mode of transmission of communicable diseases.
25. Define : Mastication
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 include drawings on paper and photographs.
3D (Three-dimensional) pictures: These have three dimensions: length, width, and depth (or height). They give the illusion of volume and space. Examples include sculptures, holograms, and images in 3D movies.
27. Differentiate mass number from atomic number.
Atomic Number (Z): It is the number of protons in the nucleus of an atom. It is unique for each element.
Mass Number (A): It is the total number of protons and neutrons in the nucleus of an atom.
28. Define. molecule.
29. What is Centre of gravity?
30. Define Stability.
III. Answer all the questions. 4x5=20
31. a) How will you determine the density of a stone using a measuring Jar?
To determine the density of a stone, we need to find its mass and volume.
- Find the Mass (m): Measure the mass of the stone using a physical balance. Let it be 'm' grams.
- Find the Volume (V):
- Take a measuring jar and fill it partially with water. Note the initial volume of water (V₁).
- Tie the stone with a thread and gently immerse it completely into the water.
- The water level will rise. Note the final volume of water (V₂).
- The volume of the stone is the difference between the final and initial readings: V = V₂ - V₁.
- Calculate Density (ρ): Use the formula:
Density (ρ) = Mass (m) / Volume (V)
The unit of density will be g/cm³.
(or)
b) Explain the types of Stability with suitable examples?
There are three types of stability:
- Stable Equilibrium: An object is in stable equilibrium if it returns to its original position after being slightly displaced. This happens when its centre of gravity is at its lowest possible position.
Example: A book lying flat on a table. - Unstable Equilibrium: An object is in unstable equilibrium if it does not return to its original position and topples over when slightly displaced. This happens when its centre of gravity is at its highest position.
Example: A cone balanced on its tip. - Neutral Equilibrium: An object is in neutral equilibrium if it stays in the new position when displaced. Its centre of gravity remains at the same height.
Example: A ball rolling on a flat horizontal surface.
32. a) Differentiate metals and non-metals?
| Property | Metals | Non-Metals |
|---|---|---|
| State | Generally solid at room temperature (except Mercury). | Exist as solids, liquids, or gases. |
| Lustre | Have a shiny appearance. | Have a dull appearance (except iodine). |
| Malleability | Can be beaten into thin sheets. | Brittle, cannot be beaten into sheets. |
| Ductility | Can be drawn into wires. | Not ductile. |
| Conductivity | Good conductors of heat and electricity. | Poor conductors (except graphite). |
(or)
b) Draw the structure of an atom and explain the position of the sub-atomic particles.
(A diagram should be drawn showing a central nucleus with protons and neutrons, and electrons in orbits around it.)
Explanation of Structure and Position:
An atom consists of a central nucleus and electrons that revolve around the nucleus in specific paths called orbits or shells.
- Protons (p⁺): These are positively charged particles. They are located inside the dense, central part of the atom called the nucleus.
- Neutrons (n⁰): These are neutral particles with no charge. They are also located inside the nucleus along with the protons.
- Electrons (e⁻): These are negatively charged particles. They are much lighter than protons and neutrons and revolve at high speed in specific orbits or shells around the nucleus.
33. a) Explain the underground stems.
Underground stems are modified stems that grow beneath the soil surface. They primarily function in food storage and vegetative propagation. The main types are:
- Rhizome: A thick, horizontal underground stem with distinct nodes and internodes. It has scale leaves and buds. Example: Ginger, Turmeric.
- Corm: A fleshy, spherical or flattened underground stem which is a condensed form of a rhizome. It stores food. Example: Colocasia.
- Tuber: A swollen, fleshy tip of an underground stem branch that stores a large amount of food (starch). It has buds called 'eyes'. Example: Potato.
- Bulb: A short, underground stem with fleshy scale leaves that store food. The stem is reduced to a disc-like structure. Example: Onion, Garlic.
(or)
b) Write a brief account on Pollination.
Pollination is the process of transferring pollen grains from the male part of a flower (anther) to the female part (stigma).
Types of Pollination:
- Self-Pollination: The transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant.
- Cross-Pollination: The transfer of pollen 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 facilitated by various agents, including:
- Wind (Anemophily): e.g., Maize, Grass
- Insects (Entomophily): e.g., Sunflower, Rose
- Water (Hydrophily): e.g., Vallisneria
- Birds (Ornithophily): e.g., Hibiscus
34. a) Write about any three communicable disease?
Three common communicable diseases are:
- Tuberculosis (TB):
- Causative Agent: Bacterium (*Mycobacterium tuberculosis*).
- Transmission: Spreads through the air via droplets from the coughs or sneezes of an infected person.
- Symptoms: Persistent cough, fever, night sweats, weight loss.
- Cholera:
- Causative Agent: Bacterium (*Vibrio cholerae*).
- Transmission: Spreads through contaminated food and water.
- Symptoms: Severe watery diarrhea, vomiting, dehydration.
- Common Cold:
- Causative Agent: Virus (Rhinovirus).
- Transmission: Spreads through droplets from coughs/sneezes or direct contact with an infected person.
- Symptoms: Runny nose, sneezing, sore throat, cough.
(or)
b) How the diseases are transmitted from person to the other person?
Diseases are transmitted from one person to another through various modes:
- Direct Transmission:
- Direct Contact: Through physical contact like touching, kissing (e.g., skin infections, common cold).
- Droplet Infection: By inhaling droplets expelled during coughing, sneezing, or talking by an infected person (e.g., Influenza, COVID-19, TB).
- Indirect Transmission:
- Airborne Transmission: When microorganisms remain suspended in the air for a long time and are inhaled (e.g., Measles).
- Contaminated Food and Water: By consuming food or water contaminated with pathogens (e.g., Cholera, Typhoid).
- Vectors: Through insects or animals that carry the pathogen from an infected person to a healthy one (e.g., Mosquitoes transmit Malaria and Dengue).
- Fomites: Through contact with contaminated objects like clothes, utensils, doorknobs (e.g., Common cold).