Physics MCQ for Competitive Exams [Set-5]

[MCQ 21] Molar density is expressed by which unit?

[A] gram molecule / liter
[B] gram / liter.
[C] pound / liter
[D] kg / lite

[Answer]

[A] gram molecule / liter

[MCQ 22] What is the number of molecules 9 g water?

[A] 3.011 × 10²²
[B] 6.023 × 10²⁴
[C] 3.011 × 10²³
[D] 6.023 × 10²¹

[Answer]

[C] 3.011 × 10²³

[MCQ 23] What is the source of solar energy?

[A] Explosion
[B] Nuclear fission.
[C] Presence of combustible material
[D] Nuclear fusion

[Answer]

[D] Nuclear fusion

[MCQ 24] Which of the seven colors of the rainbow has the longest wavelength?

[A] Blue
[B] red
[C] green
[D] Yellow

[Answer]

[B] red

[MCQ 25] What kind of substance is air?

[A] Compounds
[B] mixture
[C] elemental matter
[D] variable

[Answer]

[A] Compounds

[MCQ 26] In which unit the size of atom is measured?

[A] Angstrom
[B] Light year
[C] Parsec
[D] Heartz

[Answer]

[A] Angstrom

[MCQ 27] Insulators are bad conductors of electricity, because:

[A] Insulators do not contain free electrons.
[B] Insulators molecules are very light type
[C] Insulators have a very high melting point
[D] Insulators contain free electrons

[Answer]

[A] Insulators do not contain free electrons.

[MCQ 28] Which of the following is a scalar quantity?

[A] Force
[B] pressure
[C] velocity.
[D] Acceleration

[Answer]

[B] pressure

[MCQ 29] In which cases is the rectifier used?

[A] Convert from D.C. to A.C current.
[B] Convert from A.C. to D.C. current
[C] Conversion from high voltage to low voltage 1
[D] Conversion from low voltage to high voltage

[Answer]

[B] Convert from A.C. to D.C. current

[MCQ 30] Radar is used in which of the following cases?

[A] Determining the position of a sunken ship
[B] Receiving a signal from a radio receiver
[C] Determining the position of geostationary satellites
[D] Determining the position of a flying object, such as an airplane.

[Answer]

[D] Determining the position of a flying object, such as an airplane.