📘 Chapter 1 – The Ever-Evolving World of Science

Part 3: MCQs (Q51–Q75)

Sub-Topics: Introduction to Science, Science in Everyday Life

Q51. Which of these inventions works on the principle of electromagnetic induction?

A) Electric generator
B) Electric bulb
C) Electric heater
D) Solar panel

✅ Correct Answer: A) Electric generator

Explanation:

• A) Electric generator – Correct, generates electricity by electromagnetic induction.
• B) Electric bulb – Works on heating effect, not induction.
• C) Heater – Converts electricity into heat.
• D) Solar panel – Converts solar energy into electricity.

Q52. Which branch of science studies heredity and variation in living beings?

A) Genetics
B) Botany
C) Zoology
D) Geology

✅ Correct Answer: A) Genetics

Explanation:

• A) Genetics – Correct, studies heredity and variation.
• B) Botany – Studies plants.
• C) Zoology – Studies animals.
• D) Geology – Studies Earth’s structure.

Q53. Which everyday object uses the principle of refraction of light?

A) Mirror
B) Lens in spectacles
C) Television
D) Fan

✅ Correct Answer: B) Lens in spectacles

Explanation:

• A) Mirror – Works on reflection, not refraction.
• B) Lens – Correct, bends light rays to correct vision.
• C) Television – Works on electronic signals, not directly refraction.
• D) Fan – Mechanical device, not related to refraction.

Q54. Which of these is an example of energy conversion in a solar cooker?

A) Electrical → Mechanical
B) Solar → Heat
C) Chemical → Heat
D) Nuclear → Electrical

✅ Correct Answer: B) Solar → Heat

Explanation:

• A) Electrical → Mechanical – Not in a solar cooker.
• B) Solar → Heat – Correct, sunlight is converted into heat energy.
• C) Chemical → Heat – Happens during burning fuel, not here.
• D) Nuclear → Electrical – Nuclear power plants, not solar cooker.

Q55. Which Indian scientist is associated with missile technology?

A) Homi Bhabha
B) C.V. Raman
C) A.P.J. Abdul Kalam
D) S. Chandrasekhar

✅ Correct Answer: C) A.P.J. Abdul Kalam

Explanation:

• A) Homi Bhabha – Nuclear research.
• B) Raman – Nobel Prize in physics.
• C) Abdul Kalam – Correct, “Missile Man of India.”
• D) Chandrasekhar – Astrophysics.

Q56. Which of the following is NOT a man-made fibre?

A) Nylon
B) Rayon
C) Cotton
D) Polyester

✅ Correct Answer: C) Cotton

Explanation:

• A) Nylon – Man-made.
• B) Rayon – Semi-synthetic.
• C) Cotton – Correct, natural fibre from plants.
• D) Polyester – Synthetic.

Q57. Which gas is released during respiration in humans?

A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Hydrogen

✅ Correct Answer: C) Carbon dioxide

Explanation:

• A) Oxygen – Inhaled, not released.
• B) Nitrogen – Inert, neither used nor released much.
• C) Carbon dioxide – Correct, exhaled after respiration.
• D) Hydrogen – Not involved.

Q58. Which instrument is used to measure humidity in air?

A) Barometer
B) Hygrometer
C) Thermometer
D) Anemometer

✅ Correct Answer: B) Hygrometer

Explanation:

• A) Barometer – Pressure.
• B) Hygrometer – Correct, measures moisture in air.
• C) Thermometer – Temperature.
• D) Anemometer – Wind speed.

Q59. Which of these shows the use of friction in daily life?

A) Writing with a pen
B) Sliding on ice
C) Free fall of stone
D) Floating of wood

✅ Correct Answer: A) Writing with a pen

Explanation:

• A) Writing with pen – Correct, friction between paper and pen enables writing.
• B) Sliding on ice – Friction is low, so not useful.
• C) Free fall – Gravity, not friction.
• D) Floating of wood – Due to buoyancy, not friction.

Q60. Which scientist proposed the theory of evolution by natural selection?

A) Charles Darwin
B) Gregor Mendel
C) Isaac Newton
D) Louis Pasteur

✅ Correct Answer: A) Charles Darwin

Explanation:

• A) Darwin – Correct, explained evolution.
• B) Mendel – Father of genetics.
• C) Newton – Laws of motion.
• D) Pasteur – Germ theory.

Q61. Which is an example of a conductor of electricity?

A) Plastic
B) Wood
C) Copper
D) Rubber

✅ Correct Answer: C) Copper

Explanation:

• A) Plastic – Insulator.
• B) Wood – Poor conductor.
• C) Copper – Correct, excellent conductor.
• D) Rubber – Insulator.

Q62. Which simple machine is present in a pair of scissors?

A) Pulley
B) Lever
C) Inclined plane
D) Wedge

✅ Correct Answer: B) Lever

Explanation:

• A) Pulley – Not used.
• B) Lever – Correct, scissors act as double levers.
• C) Inclined plane – Not related.
• D) Wedge – Blade edge has wedge, but main action is lever.

Q63. Which device converts sound energy into electrical signals?

A) Speaker
B) Microphone
C) Battery
D) Camera

✅ Correct Answer: B) Microphone

Explanation:

• A) Speaker – Opposite: converts electrical to sound.
• B) Microphone – Correct, sound → electrical.
• C) Battery – Chemical → electrical.
• D) Camera – Light → image, not sound.

Q64. Which of the following is NOT a renewable source of energy?

A) Wind
B) Solar
C) Petroleum
D) Hydropower

✅ Correct Answer: C) Petroleum

Explanation:

• A) Wind – Renewable.
• B) Solar – Renewable.
• C) Petroleum – Correct, fossil fuel, non-renewable.
• D) Hydropower – Renewable.

Q65. Which gas is used by green plants during photosynthesis?

A) Oxygen
B) Carbon dioxide
C) Nitrogen
D) Hydrogen

✅ Correct Answer: B) Carbon dioxide

Explanation:

• A) Oxygen – Released, not used.
• B) Carbon dioxide – Correct, used to prepare food.
• C) Nitrogen – Not directly used.
• D) Hydrogen – Not absorbed from air.

Q66. Which part of science studies non-living things?

A) Biology
B) Physics and Chemistry
C) Zoology
D) Botany

✅ Correct Answer: B) Physics and Chemistry

Explanation:

• A) Biology – Living beings.
• B) Physics & Chemistry – Correct, deal with matter, energy, non-living things.
• C) Zoology – Animals.
• D) Botany – Plants.

Q67. Which of these helps in preventing food spoilage?

A) Freezing
B) Adding preservatives
C) Pasteurization
D) All of the above

✅ Correct Answer: D) All of the above

Explanation:

• A) Freezing – Slows bacterial growth.
• B) Preservatives – Prevent spoilage.
• C) Pasteurization – Kills microbes.
• D) All – Correct, all methods used.

Q68. Which type of energy conversion takes place in an electric bulb?

A) Electrical → Heat + Light
B) Heat → Electrical
C) Mechanical → Heat
D) Chemical → Mechanical

✅ Correct Answer: A) Electrical → Heat + Light

Explanation:

• A) Correct, bulb converts electricity into light (and some heat).
• B) Heat → Electrical – Happens in thermoelectric devices.
• C) Mechanical → Heat – Not in bulb.
• D) Chemical → Mechanical – Not in bulb.

Q69. Which scientist is famous for work on vaccination?

A) Robert Hooke
B) Edward Jenner
C) Alexander Fleming
D) Galileo Galilei

✅ Correct Answer: B) Edward Jenner

Explanation:

• A) Hooke – Cells.
• B) Jenner – Correct, invented smallpox vaccine.
• C) Fleming – Penicillin.
• D) Galileo – Astronomy, physics.

Q70. Which of these is NOT a step in the scientific method?

A) Observation
B) Hypothesis
C) Blind belief
D) Experiment

✅ Correct Answer: C) Blind belief

Explanation:

• A) Observation – Step 1.
• B) Hypothesis – Proposed explanation.
• C) Blind belief – Correct, unscientific.
• D) Experiment – Essential step.

Q71. Which of these shows the use of pressure in daily life?

A) Cutting vegetables with knife
B) Sleeping on bed
C) Drinking water from bottle
D) Listening to music

✅ Correct Answer: A) Cutting vegetables with knife

Explanation:

• A) Knife – Correct, sharp edge increases pressure, cuts easily.
• B) Sleeping – Pressure spreads, but not main example.
• C) Drinking – More suction, not pressure.
• D) Music – Sound waves, not pressure.

Q72. Which scientist proposed the heliocentric theory?

A) Galileo
B) Copernicus
C) Newton
D) Einstein

✅ Correct Answer: B) Copernicus

Explanation:

• A) Galileo – Supported the theory with telescope.
• B) Copernicus – Correct, proposed Sun-centered solar system.
• C) Newton – Gravity.
• D) Einstein – Relativity.

Q73. Which of these is an example of chemical energy in daily life?

A) Battery
B) Torch light
C) Moving fan
D) Bulb glowing

✅ Correct Answer: A) Battery

Explanation:

• A) Battery – Correct, stores chemical energy.
• B) Torch light – Uses electrical energy.
• C) Fan – Mechanical energy.
• D) Bulb – Light energy.

Q74. Which branch of science deals with the study of Earth’s atmosphere and weather?

A) Geology
B) Meteorology
C) Astronomy
D) Ecology

✅ Correct Answer: B) Meteorology

Explanation:

• A) Geology – Earth’s rocks, not weather.
• B) Meteorology – Correct, atmosphere, weather, climate.
• C) Astronomy – Space.
• D) Ecology – Relation of organisms with environment.

Q75. Which invention made long-distance communication possible using electricity?

A) Telegraph
B) Microscope
C) Camera
D) Calculator

✅ Correct Answer: A) Telegraph

Explanation:

• A) Telegraph – Correct, first electrical long-distance communication.
• B) Microscope – For tiny objects.
• C) Camera – For pictures.
• D) Calculator – For arithmetic.

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