Railway RRB / NTPC — MCQ Practice Questions & Answers

Question 1

Which of the following is a vector quantity?

Accepted Answer

Correct answer: C. Velocity — Velocity is a vector quantity as it has both magnitude and direction. Speed, temperature, and distance are scalar quantities.

Answer

A. Speed

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B. Temperature

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D. Distance

Question 2

The phenomenon where light bends while passing from one medium to another is called:

Accepted Answer

Correct answer: B. Refraction — Refraction is the bending of light when it passes from one transparent medium to another with different optical density.

Answer

A. Reflection

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C. Diffraction

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D. Dispersion

Question 3

Which element is the most abundant in the Earth's crust?

Accepted Answer

Correct answer: B. Oxygen — Oxygen is the most abundant element in Earth's crust, comprising about 46% of its composition.

Answer

A. Iron

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C. Silicon

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D. Aluminum

Question 4

The theory that explains the motion of planets around the sun is:

Accepted Answer

Correct answer: B. Kepler's Laws of Planetary Motion — Kepler's Laws of Planetary Motion describe how planets orbit the sun in elliptical paths with the sun at one focus.

Answer

A. Newton's First Law

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C. Law of Conservation of Energy

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D. Coulomb's Law

Question 5

In the context of railways, which type of braking system provides the fastest stopping power?

Accepted Answer

Correct answer: D. Magnetic track brakes — # Railway Braking Systems: Stopping Power Analysis To identify the fastest braking system, we must compare the deceleration capability and stopping distance of each braking method used in railways. ## Step 1: Understand Air Brake System Air brakes operate by converting compressed air pressure into mechanical friction on brake pads against wheels. While reliable and widely used, they depend on friction coefficients and require time for pressure buildup across the train. **Deceleration achieved:** a_{	ext{air}} \approx 0.8	ext{–}1.0\,	ext{m/s}^2 ## Step 2: Compare Hydraulic Brake System Hydraulic brakes use fluid pressure transmission, providing quick response and good modulation. However, they are less common in modern railways and provide similar or slightly lower deceleration than air brakes. **Deceleration achieved:** a_{	ext{hydraulic}} \approx 0.6	ext{–}0.9\,	ext{m/s}^2 ## Step 3: Evaluate Regenerative Brake System Regenerative brakes convert kinetic energy back into electrical energy (stored in pantograph or batteries). They are e

Answer

A. Air brake

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B. Hydraulic brake

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C. Regenerative brake

Question 6

Which of the following is an example of a heterogeneous mixture?

Accepted Answer

Correct answer: C. Sand and iron filings — Sand and iron filings form a heterogeneous mixture as their components remain visibly distinct and can be easily separated.

Answer

A. Salt solution

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B. Sugar solution

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D. Alcohol and water

Question 7

What is the Doppler effect primarily related to?

Accepted Answer

Correct answer: B. Change in frequency or wavelength of waves due to relative motion — The Doppler effect describes the change in frequency or wavelength of waves when the source or observer moves relative to each other.

Answer

A. Change in density

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C. Change in amplitude

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D. Change in intensity

Question 8

Which type of lens is used to correct myopia (short-sightedness)?

Accepted Answer

Correct answer: B. Concave lens — Concave lenses are used to correct myopia by diverging light rays to focus them correctly on the retina.

Answer

A. Convex lens

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C. Bifocal lens

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D. Cylindrical lens

Railway RRB / NTPC - MCQ Practice Questions