Class 8 Science Question Paper Solution(24-25)-English Medium
Section-A
1. Very Short Answer Type Questions
Q (i): Natural gas is an exhaustible natural resource. (True/False)
Answer: True
Q (ii): ______ water is a poor conductor of electricity because it is free of salts.
Answer: Distilled Water
Q (iii): The ______ of a force is measured by its magnitude.
Answer: Strength
Q (iv): A deflection can be seen in a magnetic needle even when the electric current is very weak. (True/False)
Answer: True (LEDs or magnetic compasses are used to detect this).
Q (v): Name any two crops grown from October to March.
Answer: Wheat and Gram (These are Rabi crops).
Q (vi): When electric current is passed through Copper Sulphate solution, it dissociates into ______ and ______.
Answer: Copper and Sulphate.
Q (vii): Name two modern methods of irrigation.
Answer: (1) Sprinkler System, (2) Drip System.
OR
What is ‘Dhekli’?
Answer: It is a traditional method of irrigation in which water is drawn from a well using a lever system.
Q (viii): Name a solution through which electric current can pass.
Answer: Salt solution or Lemon water.
Q (ix): Complete the formula: Pressure = ‘a’ / Area on which it acts. Identify ‘a’.
Answer: a = Force (Pressure = Force / Area)
Q (x): The force exerted by a magnet is an example of a contact force. (True/False)
Answer: False (It is a non-contact force).
Q (xi): Describe the lateral inversion of the English letter ‘B’.
Answer: In a mirror, the left side of ‘B’ will appear on the right side (It will look like a reversed B).
Q (xii): Liquids exert pressure on the walls of the container. (True/False)
Answer: True.
OR
Force comes into play due to interaction between two objects. (True/False)
Answer: True.
Section-B
Short Answer Type Questions
Q 2: Name any two Protozoa.
Answer: Amoeba and Paramecium.
OR
Name two diseases caused by bacteria.
Answer: Cholera and Typhoid.
Q 3: Name a constituent of petroleum and write one use of it.
Answer: Constituent: Petrol. Use: As motor fuel. (Alternatively: Bitumen – used for paints/road surfacing).
Q 4: If the amplitude of the vibration producing sound is doubled, what will be the effect on the loudness of the sound?
Answer: The loudness will increase by 4 times (Because loudness is proportional to the square of the amplitude).
OR
(i) Give an example for: ‘If the frequency of vibration is low, the pitch of the sound will be low.’
Answer: A lion’s roar (Low frequency = Low pitch/Deep voice) vs. A mosquito’s buzzing (High frequency = High pitch).
(ii) Write the unit of frequency.
Answer: Hertz (Hz).
Q 5: Write any two 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.
Q 6: Is it easier to cut vegetables with a blunt knife or a sharp knife? Why?
Answer: It is easier to cut with a sharp knife because its surface area is smaller. This means less force is required to exert higher pressure.
OR
Identify the force of attraction that acts on every object and give an example.
Answer: Gravitational Force. Example: A fruit falling down from a tree.
Q 7: List two measures to prevent the spread of malaria.
Answer: (1) Use mosquito nets. (2) Do not let water stagnate in the surroundings (to prevent mosquito breeding).
Q 8: What are ‘Petrochemicals’? Write two uses.
Answer: Chemical substances obtained from petroleum and natural gas are called petrochemicals.
Uses: (1) In making detergents. (2) In making polyester/nylon (synthetic fibres).
Uses: (1) In making detergents. (2) In making polyester/nylon (synthetic fibres).
OR
Write any three uses of natural gas.
Answer: (1) As CNG fuel in vehicles. (2) For electricity generation. (3) As domestic fuel (piped gas) in homes.
Q 9: List the various steps involved in crop production.
Answer: (1) Preparation of soil, (2) Sowing, (3) Adding manure and fertilizers, (4) Irrigation, (5) Protection from weeds, (6) Harvesting, (7) Storage.
OR
How is a seed-drill better than traditional sowing tools? (Write any three points).
Answer: (1) It maintains equal distance and depth between seeds. (2) Seeds get covered by soil (protecting them from birds). (3) It saves time and labor.
Q 10: Why is a layer of chromium deposited on cheaper metals? Give any three reasons.
Answer: (1) It protects the metal from rusting/corrosion. (2) It gives the object a shiny appearance. (3) It resists scratches.
Q 11 (i): Can reflected light be reflected again? Give a real-life example.
Answer: Yes. Example: In a hair salon, a second mirror is used behind you so you can see the back of your head.
Q 11 (ii): How many plane mirrors are used in a periscope?
Answer: Two (2) plane mirrors.
Q 11 (iii): Write one use of a periscope.
Answer: It is used in submarines to see objects/movements above the sea surface.
Section-C
12. Correct Match
| Seq | Question | Correct Match (Answer) |
|---|---|---|
| (i) | Viviparous Animals | (e) Give birth to young ones. |
| (ii) | Metamorphosis | (a) Transformation of larva into adult. |
| (iii) | Asexual Reproduction | (b) Only a single parent is involved. |
| (iv) | Fertilization | (f) Fusion of egg and sperm. |
| (v) | Oviparous Animals | (c) Lay eggs. |
| (vi) | Foetus | (d) All body parts become identifiable. |
13. Paragraph Based Questions (Sound)
Q (i): Sound cannot travel in ______.
Answer: (B) Vacuum (Sound needs a medium to travel).
Q (ii): The loudness of normal conversation is ______.
Answer: (C) 60 dB
Q (iii): The audible frequency range for human ears is approximately…
Answer: (A) 20 Hz to 20,000 Hz
OR
In humans, sound is produced by the vibration of the ______.
Answer: (D) Vocal cords
14. Paragraph Based Questions (Nutrition)
Q (i): ______ is an insectivorous plant.
Answer: (A) Pitcher Plant
Q (ii): The ultimate source of energy for all living organisms is the ______.
Answer: (C) Sun
Q (iii): ______ helps in capturing solar energy.
Answer: (D) Chlorophyll
OR
Starch is a type of ______.
Answer: (A) Carbohydrate
15. Paragraph Based Questions (Adaptation)
Q (i): The surroundings where an organism lives is called its ______.
Answer: (B) Habitat
Q (ii): ______ is a desert animal.
Answer: (A) Camel
Q (iii): Desert animals come out at night because at night the temperature is ______.
Answer: (C) Lower than normal (It is cooler).
OR
The thick waxy layer in desert plants helps in conserving ______.
Answer: (A) Water (To prevent water loss).
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