7th Science First Term Question Paper with Answers 2024 | Krishnagiri District | Samacheer Kalvi
Standard: 7 - Std
Subject: SCIENCE
Time: 2.00 Hrs.
Marks: 60
1. SI unit of density is
2. Light year is the unit of
3. Suppose the boy is enjoying a ride on a merry go round which is moving with a constant speed of 10 m/s. It is implies that boy is
4. Which one of the following is an example for a metal?
5. The metal which is liquid at room temperature is
6. ...................... is the positively charged.
7. The atomic number of an atom is the ......................
8. Reproductive parts of a plant is
9. Climbing roots are seen in
10. Our living place should be
11. Fill in the blanks.
a) One astronomical unit is equal to 149.6 million km or 1.496 x 10⁸ km.
b) The area of a leaf can be measured using a graph sheet.
12. Arrange the following in correct sequence.
a) 1L, 100CC, 10L, 10CC.
Correct Sequence (Ascending): 10CC, 100CC, 1L, 10L.
b) Copper, Alluminium, Gold, Iron.
Correct Sequence (by density - low to high): Alluminium, Iron, Copper, Gold.
13. Analogy:
a) Area : m² :: Volume : m³
b) Water : kerosene :: Iron : Aluminium. (Analogy based on density)
14. Match the following.
| Column A | Column B |
|---|---|
| a) Displacement | Metre |
| b) Light travelling through vacuum | Uniform velocity |
| c) Speed of ship | Knots |
| d) Stability | Larger base area |
15. Distinguish between speed and velocity.
| Speed | Velocity |
|---|---|
| The rate of change of distance. | The rate of change of displacement. |
| It is a scalar quantity (has only magnitude). | It is a vector quantity (has both magnitude and direction). |
16. True / False.
a) NaCl represents one molecule of sodium chloride. - True.
b) Argon is mono atomic gas. - True.
17. What are compounds? Give two examples.
Examples: Water (H₂O), Carbon dioxide (CO₂).
18. Write the chemical formula for the following elements.
a) Hydrogen - H₂
b) Nitrogen - N₂
c) Ozone - O₃
d) Sulphur - S₈
19. What are isotones? Give one example.
Example: Carbon-13 (6 protons, 7 neutrons) and Nitrogen-14 (7 protons, 7 neutrons).
20. What is atomic number?
21. Write two types of reproduction in plants.
- Sexual Reproduction: Involves the fusion of male and female gametes to produce a new organism.
- Asexual Reproduction: Does not involve the fusion of gametes. New plants are produced from vegetative parts like root, stem, or leaf.
22. What are the agents of pollination?
23. What is cross pollination?
24. What are thorns?
25. Analogy:
a) Typhoid : Bacteria :: Hepatitis : Virus
b) Tuberculosis : Air :: Cholera : Water / Food
26. What is Hygiene?
27. How to keep your hair clean and healthy?
- Wash your hair regularly with a mild shampoo.
- Keep the scalp clean to avoid dandruff.
- Eat a balanced diet rich in proteins and vitamins.
- Gently massage your scalp to improve blood circulation.
28. Give any two communicable diseases, which spread in your locality during monsoon.
1. Dengue fever (spread by mosquitoes breeding in stagnant water).
2. Cholera (spread through contaminated water).
29. What is Raster Graphics?
30. Match the following.
| Column A | Column B |
|---|---|
| a) Animations | 3D |
| b) Raster | Pixels |
| c) vector | Illustrator |
| d) Virtual Reality | Visual communication |
| e) Video story | Microsoft photostory |
31. Describe the graphical method to find the area of an irregularly shaped plane figure.
- Place the irregular object (like a leaf) on a graph sheet and trace its boundary with a pencil.
- Remove the object and count the number of complete squares enclosed by the boundary. Let this be 'M'.
- Count the number of squares that are more than half-covered. Let this be 'N'.
- Count the number of squares that are exactly half-covered. Let this be 'P'.
- Ignore the squares that are less than half-covered.
- The approximate area (A) of the object is calculated using the formula:
A = M + N + (P/2) square units (e.g., cm² or mm²).
32. Explain the types of stability with suitable examples.
- Stable Equilibrium: An object is in stable equilibrium if it returns to its original position after being slightly displaced. This happens when its center of gravity is at its lowest possible point.
Example: A book lying flat on a table, or a cone resting on its base. - Unstable Equilibrium: An object is in unstable equilibrium if it does not return to its original position after a slight displacement and instead topples over. This happens when its center of gravity is at its highest point.
Example: A pencil balanced on its tip, or a cone balanced on its apex. - Neutral Equilibrium: An object is in neutral equilibrium if it stays in its new position after being displaced. Its center of gravity remains at the same height.
Example: A ball on a horizontal surface, or a cone lying on its side.
33. List out the metals, non-metals and metalloids which you use in your house, schools, compare their properties.
Examples from daily life:
- Metals: Iron (gates, grills), Copper (electrical wires), Aluminium (utensils, foil), Gold (jewellery).
- Non-metals: Carbon (in pencil lead - graphite), Oxygen (for breathing), Chlorine (in bleach, water purification).
- Metalloids: Silicon (in computer chips, glass).
Comparison of Properties:
| Property | Metals | Non-metals | Metalloids |
|---|---|---|---|
| Lustre | Shiny (lustrous) | Dull (non-lustrous) | Can be shiny or dull |
| Conductivity | Good conductors of heat and electricity | Poor conductors (insulators) | Semiconductors |
| Malleability/Ductility | Malleable and ductile | Brittle (break easily) | Brittle |
| State at Room Temp. | Mostly solid (except Mercury) | Solid, liquid, or gas | Solid |
34. Draw the structure of an atom and explain the position of the sub-atomic particles.
Structure of an Atom (Description):
An atom consists of a central nucleus and electrons orbiting it.
• The Nucleus is at the center and contains protons and neutrons.
• The Electrons move around the nucleus in fixed paths called shells or energy levels.
Position of Sub-atomic Particles:
- Protons (p⁺): They are positively charged particles located inside the nucleus.
- Neutrons (n⁰): They have no charge (are neutral) and are also located inside the nucleus.
- Electrons (e⁻): They are negatively charged particles that revolve around the nucleus in specific orbits.
35. 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 of the flower (stigma).
Types of Pollination:
- Self-pollination: The transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant.
- Cross-pollination: 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:
- Abiotic agents (non-living): Wind and Water.
- Biotic agents (living): Insects, birds, bats, and other animals.
36. Write about any three communicable diseases in detail.
1. Tuberculosis (TB)
- Causative Agent: Bacterium called Mycobacterium tuberculosis.
- Mode of Transmission: Spreads through the air via droplets from the cough or sneezes of an infected person.
- Symptoms: Persistent cough, chest pain, fever, night sweats, and weight loss.
- Prevention: BCG vaccination, maintaining good hygiene.
2. Cholera
- Causative Agent: Bacterium called Vibrio cholerae.
- Mode of Transmission: Spreads through consumption of contaminated food or water.
- Symptoms: Severe watery diarrhea, vomiting, and rapid dehydration.
- Prevention: Drinking boiled water, proper sanitation, and washing hands before eating.
3. Common Cold
- Causative Agent: Virus, most commonly Rhinovirus.
- Mode of Transmission: Spreads through airborne droplets from an infected person's cough or sneeze, or by touching contaminated surfaces.
- Symptoms: Runny nose, sneezing, sore throat, and cough.
- Prevention: Frequent hand washing, avoiding contact with infected people.