Railway RRB / NTPC — General Science Questions & Answers

Q.1 Hard General Science

At what temperature do Celsius and Fahrenheit scales show the same numerical value?

A -20°

B -40°

C 0°

D -10°

Correct Answer: B. -40°

EXPLANATION

Using the formula F = (9/5)C + 32, when C = F, we get C = (9/5)C + 32, solving gives C = -40°

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Q.2 Hard General Science

Which of the following exhibits both wave and particle properties?

A Sound waves only

B Light only

C Light and electrons

D Water waves only

Correct Answer: C. Light and electrons

EXPLANATION

Light and electrons exhibit wave-particle duality, meaning they behave as both waves and particles depending on the experiment.

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Q.3 Hard General Science

Which of the following elements has the highest electronegativity according to the Pauling scale?

A Oxygen

B Chlorine

C Fluorine

D Nitrogen

Correct Answer: C. Fluorine

EXPLANATION

Fluorine has the highest electronegativity value (3.98) on the Pauling scale. Electronegativity is the tendency of an atom to attract electrons in a chemical bond. As we go from fluorine down the halogen group, electronegativity decreases.

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Q.4 Hard General Science

Which of the following statements about sound waves is incorrect?

A Sound travels faster in solids than in air

B Sound requires a medium to propagate

C Sound can propagate through vacuum

D Frequency of sound determines its pitch

Correct Answer: C. Sound can propagate through vacuum

EXPLANATION

Sound cannot propagate through vacuum because it requires a medium (solid, liquid, or gas) to travel. Sound travels fastest in solids, slower in liquids, and slowest in gases. Frequency determines pitch.

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Q.5 Hard General Science

Which law of thermodynamics states that energy cannot be created or destroyed?

A First law of thermodynamics

B Second law of thermodynamics

C Third law of thermodynamics

D Zeroth law of thermodynamics

Correct Answer: A. First law of thermodynamics

EXPLANATION

The First Law of Thermodynamics is the Law of Conservation of Energy, which states that energy is neither created nor destroyed but only transformed.

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Q.6 Hard General Science

According to the Doppler effect, what happens to the frequency of sound when a source moves towards an observer?

A Frequency decreases

B Frequency increases

C Frequency remains constant

D Frequency becomes zero

Correct Answer: B. Frequency increases

EXPLANATION

The Doppler effect causes the observed frequency to increase when a sound source moves towards the observer due to compression of sound waves.

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Q.7 Hard General Science

What is the focal length of a plane mirror?

A Zero

B Infinity

C Equal to radius of curvature

D Half the radius

Correct Answer: B. Infinity

EXPLANATION

A plane mirror has infinite focal length because it does not converge or diverge light rays.

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Q.8 Hard General Science

Which of the following correctly represents the order of electromagnetic spectrum from lowest to highest frequency?

A Radio, microwave, visible, X-ray, gamma

B Gamma, X-ray, visible, microwave, radio

C Visible, radio, microwave, X-ray, gamma

D X-ray, visible, radio, gamma, microwave

Correct Answer: A. Radio, microwave, visible, X-ray, gamma

EXPLANATION

The electromagnetic spectrum in order of increasing frequency: Radio < Microwave < Infrared < Visible < Ultraviolet < X-ray < Gamma.

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Q.9 Hard General Science

What is the half-life of Carbon-14, which is used in radioactive dating?

A 573 years

B 5,730 years

C 57,300 years

D 573,000 years

Correct Answer: B. 5,730 years

EXPLANATION

Carbon-14 has a half-life of approximately 5,730 years, making it useful for dating archaeological artifacts.

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Q.10 Hard General Science

At what temperature do Celsius and Fahrenheit scales show the same reading?

A -40°

B 0°

C 100°

D 40°

Correct Answer: A. -40°

EXPLANATION

At -40°, both Celsius and Fahrenheit scales show the same value: -40°C = -40°F.

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