MCQ Practice

General Science (Everyday Science) MCQs

Which statement about entropy is correct for an isolated system?

A. It always decreases
B. It remains zero
C. It cannot decrease in spontaneous processes
D. It depends only on pressure

Explanation:
The second law states entropy of an isolated system does not spontaneously decrease.

The phase difference between displacement and velocity in SHM is:

A. 0
B. (\pi/4)
C. (\pi/2)
D. (\pi)

Explanation:
Velocity leads displacement by a quarter cycle in SHM.

In a semiconductor, a p-type material is produced by doping silicon with:

A. Pentavalent atoms
B. Noble gases
C. Trivalent atoms
D. Isotopes of silicon only

Explanation:
Trivalent dopants create holes as majority carriers.

If the net external torque on a system is zero, which quantity is conserved?

A. Linear momentum only
B. Angular momentum
C. Kinetic energy only
D. Power

Explanation:
Zero external torque implies conservation of total angular momentum.

Which phenomenon demonstrates light’s wave nature most directly?

A. Photoelectric effect
B. Compton scattering
C. Diffraction
D. Pair production

Explanation:
Diffraction is a characteristic wave interference effect.

A wave function must be normalizable because it represents:

A. Electric potential
B. Probability amplitude
C. Kinetic energy density
D. Momentum flux

Explanation:
Total probability must be finite and equal to one.

In the photoelectric effect, increasing light intensity at fixed frequency above threshold increases:

A. Maximum kinetic energy of emitted electrons
B. Number of emitted electrons per unit time
C. Threshold frequency
D. Work function

Explanation:
Intensity raises photon flux, hence emission rate, but not per-electron maximum energy.

The work done by a conservative force over a closed path is:

A. Positive
B. Negative
C. Path dependent
D. Zero

Explanation:
Conservative forces have zero net work over any closed loop.

For blackbody radiation, Wien’s displacement law relates peak wavelength inversely to:

A. Pressure
B. Temperature
C. Entropy
D. Emissivity

Explanation:
The hotter the blackbody, the shorter the wavelength at which it emits most strongly.

Which quantum number set is impossible for an electron in an atom?

A. (n=3,\ l=2,\ m_l=1)
B. (n=2,\ l=2,\ m_l=0)
C. (n=4,\ l=1,\ m_l=-1)
D. (n=1,\ l=0,\ m_l=0)

Explanation:
For principal quantum number (n), the azimuthal quantum number must satisfy (0 \le l \le n-1).