Everyday Science MCQs – Set 3
Practice 20 important Everyday Science MCQs covering biology, chemistry, physics, human health, earth science, space science and environmental science. Click Show Correct Answer to reveal the answer with a short explanation.
1. Which blood cells help the body fight infections?
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Correct Answer: C. White blood cells
White blood cells are part of the immune system and help defend the body against infections and harmful foreign substances.
White blood cells are part of the immune system and help defend the body against infections and harmful foreign substances.
2. Which blood component is mainly responsible for helping blood clot?
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Correct Answer: B. Platelets
Platelets gather at damaged blood vessels and help form clots that reduce bleeding.
Platelets gather at damaged blood vessels and help form clots that reduce bleeding.
3. Which organ removes many waste products from the blood and produces urine?
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Correct Answer: B. Kidney
The kidneys filter the blood, remove many waste products and excess substances, and produce urine.
The kidneys filter the blood, remove many waste products and excess substances, and produce urine.
4. Which part of the eye controls the amount of light entering it?
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Correct Answer: C. Iris
The iris controls the size of the pupil, thereby regulating the amount of light entering the eye.
The iris controls the size of the pupil, thereby regulating the amount of light entering the eye.
5. Which structure in the ear is mainly responsible for hearing?
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Correct Answer: A. Cochlea
The cochlea contains sensory cells that convert vibrations into nerve signals used for hearing.
The cochlea contains sensory cells that convert vibrations into nerve signals used for hearing.
6. What is the chemical symbol for sodium?
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Correct Answer: C. Na
The chemical symbol Na comes from the Latin name for sodium, "natrium."
The chemical symbol Na comes from the Latin name for sodium, "natrium."
7. Which gas is necessary for most forms of combustion?
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Correct Answer: B. Oxygen
Oxygen supports combustion and is required for most ordinary burning processes.
Oxygen supports combustion and is required for most ordinary burning processes.
8. What is the chemical formula of carbon dioxide?
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Correct Answer: B. CO₂
A carbon dioxide molecule contains one carbon atom bonded to two oxygen atoms.
A carbon dioxide molecule contains one carbon atom bonded to two oxygen atoms.
9. Which substance is commonly added to water to make it safe for drinking?
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Correct Answer: A. Chlorine
Chlorine is widely used in water treatment because it helps kill or inactivate many harmful microorganisms.
Chlorine is widely used in water treatment because it helps kill or inactivate many harmful microorganisms.
10. Which type of change occurs when ice melts into water?
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Correct Answer: C. Physical change
Melting changes the physical state of water from solid to liquid without producing a new substance.
Melting changes the physical state of water from solid to liquid without producing a new substance.
11. What is the SI unit of temperature?
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Correct Answer: C. Kelvin
The kelvin (K) is the SI base unit of thermodynamic temperature.
The kelvin (K) is the SI base unit of thermodynamic temperature.
12. Which force pulls objects toward the Earth?
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Correct Answer: C. Gravitational force
Earth's gravitational force attracts objects toward its centre and gives objects their weight.
Earth's gravitational force attracts objects toward its centre and gives objects their weight.
13. Which type of lens is commonly used in a magnifying glass?
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Correct Answer: B. Convex lens
A convex lens can produce a magnified upright image when the object is placed within its focal length.
A convex lens can produce a magnified upright image when the object is placed within its focal length.
14. What is the approximate speed of light in a vacuum?
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Correct Answer: C. 3 × 10⁸ m/s
Light travels through a vacuum at approximately 300 million metres per second.
Light travels through a vacuum at approximately 300 million metres per second.
15. Which layer of the Earth lies directly beneath the crust?
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Correct Answer: C. Mantle
The mantle is the thick layer of hot rock located directly beneath Earth's crust.
The mantle is the thick layer of hot rock located directly beneath Earth's crust.
16. What is molten rock beneath the Earth's surface called?
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Correct Answer: B. Magma
Molten or partially molten rock beneath Earth's surface is called magma. When it reaches the surface, it is called lava.
Molten or partially molten rock beneath Earth's surface is called magma. When it reaches the surface, it is called lava.
17. Which planet has the most prominent ring system in the Solar System?
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Correct Answer: C. Saturn
Saturn is famous for its extensive and highly visible system of rings made mainly of ice and rocky particles.
Saturn is famous for its extensive and highly visible system of rings made mainly of ice and rocky particles.
18. What is the natural satellite of Earth?
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Correct Answer: B. Moon
The Moon is Earth's natural satellite and revolves around Earth.
The Moon is Earth's natural satellite and revolves around Earth.
19. Which process describes the loss of water vapour from plant leaves?
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Correct Answer: B. Transpiration
Transpiration is the loss of water vapour from plant surfaces, especially through tiny openings called stomata in leaves.
Transpiration is the loss of water vapour from plant surfaces, especially through tiny openings called stomata in leaves.
20. Which gas is a major greenhouse gas released by human activities?
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Correct Answer: A. Carbon dioxide
Carbon dioxide is a major greenhouse gas, and human activities such as burning fossil fuels increase its concentration in the atmosphere.
Carbon dioxide is a major greenhouse gas, and human activities such as burning fossil fuels increase its concentration in the atmosphere.
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