Class 7 Natural Science – 23-24
Solved Question Paper
Section-A
1. (i) Digestion of starch begins in the stomach. (True/False)
Answer: False (Explanation: Digestion of starch begins in the mouth itself.)
1. (ii) Raw mango contains a large amount of acid. (True/False)
Answer: True
1. (iii) The basic unit of time is the second. (True/False)
Answer: True
1. (iv) A real image cannot be obtained on a screen. (True/False)
Answer: False (Explanation: A real image can be obtained on a screen.)
1. (v) Food synthesized by plants is stored in the form of ……. .
Answer: Starch
1. (vi) With lime water, phenolphthalein shows ……. color.
Answer: Pink
1. (vii) Changes in which only the ……. properties of a substance change are called physical changes.
Answer: Physical
1. (viii) Dry wood is a/an ……. of electricity.
Answer: Insulator
1. (ix) Name one autotroph.
Answer: Green Plants or Algae
— OR —
Write the names of any two nutrients.
Answer: Carbohydrates, Proteins.
1. (x) Define the element found in electric appliances.
Answer: Electric heaters or other incandescent appliances have a coil of wire that gets hot when electric current flows through it; this is called the Heating Element.
— OR —
Name an electric device that contains an element.
Answer: Electric Heater or Electric Iron.
1. (xi) Name a device in which a battery is used.
Answer: Torch, Transistor, or Remote Control.
— OR —
What is a battery?
Answer: A combination of two or more cells is called a battery.
1. (xii) Which type of mirror can form a real image?
Answer: Concave Mirror.
— OR —
The inner surface of a steel spoon acts like which mirror?
Answer: Concave Mirror.
Section-B
2. What do you understand by a symbiotic relationship?
Answer: Some organisms live together and share both shelter (living space) and nutrients. This is called a symbiotic relationship. Example: Lichens (association between fungus and alga).
3. Which part of the alimentary canal performs the following activities?
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(i) Absorption of digested food
Answer: Small Intestine.
(ii) Chewing of food
Answer: Buccal Cavity (Teeth).
— OR —
Name any four parts of the human digestive system.
Answer: (1) Buccal Cavity, (2) Oesophagus (Food Pipe), (3) Stomach, (4) Small Intestine.
4. State any two differences between acids and bases.
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Answer:
- Acids are sour in taste, whereas bases are bitter in taste.
- Acids turn blue litmus red, whereas bases turn red litmus blue.
— OR —
Name any two acids and two bases.
Answer:
- Acids: Hydrochloric acid (HCl), Sulphuric acid (H2SO4).
- Bases: Sodium hydroxide (NaOH), Potassium hydroxide (KOH).
5. Draw symbols for the following:
(i) Switch in ‘OFF’ position
Answer: In the symbol, the wire will appear disconnected (open circuit).
(ii) Electric bulb
Answer: Diagram of a filament inside a circle.
(For Visually Impaired Students): Why do we cover the plug pin holes with cellotape or plastic covers when not in use?
Answer: To prevent Electric Shock, because plastic is an insulator of electricity.
6. Define the heating effect of electric current.
Answer: When an electric current flows through a wire, the wire gets heated. This is called the heating effect of electric current.
7. Write the difference between convex and concave lenses.
Answer:
- Convex Lens: Thicker in the middle and thinner at the edges (Converging).
- Concave Lens: Thinner in the middle and thicker at the edges (Diverging).
8. Identify the technical term associated with the following statements:
(i) A parasitic plant with a yellow, slender stem.
Answer: Cuscuta (Amarbel).
(ii) A plant that has both autotrophic and heterotrophic modes of nutrition.
Answer: Pitcher Plant.
(iii) The pores through which exchange of gases takes place in leaves.
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Answer: Stomata.
— OR —
Describe the process of photosynthesis.
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Answer: The process by which green plants make their own food (carbohydrates) using carbon dioxide and water in the presence of sunlight and chlorophyll, and release oxygen.
9. Match the following:
| Column-I | Column-II (Correct Answer) |
|---|---|
| (a) Carbohydrates | (ii) Sugar |
| (b) Protein | (iii) Amino Acid |
| (c) Fat | (i) Fatty acids and Glycerol |
10. Explain the process of neutralization with an example.
Answer: The reaction between an acid and a base is known as neutralization. In this process, salt and water are produced with the evolution of heat. Example: HCl + NaOH → NaCl + H2O + Heat
11. Write three characteristics of the image formed by a plane mirror.
Answer: (1) The image is erect (upright). (2) The image is of the same size as the object. (3) The image is virtual (formed behind the mirror).
— OR —
How many colors are there in a rainbow? Write their names.
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Answer: 7 colors: Red, Orange, Yellow, Green, Blue, Indigo, Violet.
Section-C
12. Classify the following changes as physical or chemical changes:
- (a) Photosynthesis: Chemical Change
- (b) Dissolving sugar in water: Physical Change
- (c) Burning of coal: Chemical Change
- (d) Melting of wax: Physical Change
- (e) Beating aluminium to make foil: Physical Change
- (f) Digestion of food: Chemical Change
13. (Passage based question: Motion and Distance)
(i) The basic unit of distance is-
Answer: (a) m (meter)
(ii) Speed is –
Answer: (a) Distance / Time
(iii) Time can be measured by –
Answer: (d) All of the above
— OR —
Distance covered in unit time is-
Answer: (b) Speed
14. (Passage based question: Vitamins)
(i) Which of the following is not a vitamin?
Answer: (d) Vitamin Z
(ii) Deficiency of Vitamin A causes ……. disease.
Answer: (c) Night Blindness
(iii) Which vitamin is essential for bones and teeth?
Answer: (a) Vitamin D
— OR —
Nutrient that gives energy –
Answer: (a) Fats
15. (Passage based question: Transparent and Opaque Objects)
(i) Example of an opaque object is –
Answer: (d) All of the above
(ii) We can see through ……. objects.
Answer: (a) Transparent
(iii) Light travels in a –
Answer: (a) Straight Line
— OR —
……. is a transparent object.
Answer: (b) Glass
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