The number of protons in an atom determines its MCQ with Answer and Explanation

Question Report Error

The number of protons in an atom determines its

A. Isotope

B. Neutron number

C. Atomic number

D. Mass number

Answer: Option C

Solution (By JKExamLibrary)

Atomic number Z = number of protons. Defines chemical element. Mass number = protons + neutrons. Isotopes same Z, different neutrons. Isobars same A, different Z.

This question belongs to: Science Physics

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Practice More Physics Questions

Question #1 Report Error

Series LCR at resonance: impedance is:

A. Minimum (=R)

B. Maximum

C. Infinite

D. Zero

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Correct Answer: Option A

Explanation:
Resonance: X_L = X_C ⇒ they cancel ⇒ Z = R (minimum). Current maximum at resonance. Memory tip: 'Series resonance: Z_min = R; parallel: Z_max'. AC circuit concept frequently tested in competitive exams.

This question belongs to: Science Physics

Question #2 Report Error

A pump lifts 100 kg of water through 5 m in 2 s. Power (g=10) is

A. 500 W

B. 2500 W

C. 1000 W

D. 250 W

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Correct Answer: Option B

Explanation:
Work = 100×10×5=5000 J. Power = 5000/2 = 2500 W.

This question belongs to: Science Physics

Question #3 Report Error

Assertion (A): The velocity of sound is greater in solids than in gases. Reason (R): Solids possess higher elasticity compared to gases.

A. A is true but R is false.

B. A is false but R is true.

C. Both A and R are true and R is the correct explanation of A.

D. Both A and R are true but R is NOT the correct explanation of A.

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Correct Answer: Option C

Explanation:
The velocity of sound in a medium is determined by the formula v = √(E/ρ), where E is the modulus of elasticity and ρ is the density. Although solids are denser, their modulus of elasticity (bulk modulus) is tremendously higher than that of gases, overwhelmingly compensating for the density. Hence, sound travels fastest in solids.

This question belongs to: Science Physics

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