Home Subjects Railway RRB / NTPC

Railway RRB / NTPC

NTPC, Group D, JE — all sections

79 Q 5 Topics Take Test
Advertisement
Difficulty: All Easy Medium Hard 61–70 of 79
Topics in Railway RRB / NTPC
Q.61 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.

Take Test
Q.62 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.

Take Test
Q.63 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.

Take Test
Q.64 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.

Take Test
Q.65 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.

Take Test
Q.66 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.

Take Test
Q.67 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.

Take Test
Q.68 Hard General Science
At what temperature do Celsius and Fahrenheit scales show the same reading?
A -40°
B
C 100°
D 40°
Correct Answer:  A. -40°
EXPLANATION

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

Take Test
Q.69 Hard General Science
Which gas is used in welding and cutting of metals?
A Nitrogen
B Oxygen
C Acetylene
D Hydrogen
Correct Answer:  C. Acetylene
EXPLANATION

Acetylene (C₂H₂) is commonly used in oxy-acetylene welding and cutting due to its high flame temperature of about 3,300°C.

Take Test
Q.70 Hard General Science
What is the process by which an electric current is generated using a magnetic field?
A Magnetization
B Electromagnetic induction
C Polarization
D Ionization
Correct Answer:  B. Electromagnetic induction
EXPLANATION

Electromagnetic induction is the process where a changing magnetic field produces an electric current, as discovered by Faraday.

Take Test
IGET
iget AI
Online · Ask anything about exams
Hi! 👋 I'm your iget AI assistant.

Ask me anything about exam prep, MCQ solutions, study tips, or strategies! 🎯
UPSC strategy SSC CGL syllabus Improve aptitude NEET Biology tips