Physics Mcq Questions | Psc, wbcs exam physics MCQ | rlearn


1. Light year is a measurement of

A. Speed of aeroplanes

B. Speed of light

C. Stellar distances

D. Speed of rockets

Answer: Option C

Explanation :A light-year is a unit of distance. It is the distance a light photon travels in the vacuum in one Julian year. The distance that light travels in one year, about 9.4607×10¹² kilometres.
2.Kilohertz is a unit which measures

A. Power used by a current of one ampere—

B. Electromagnetic radio wave frequencies

C. Voltage

D. Electric resistance

Answer: Option B

  1. One kilometer is equal to how many miles?

A. 0.84

B. 0.5

C. 1.6

D. 0.62

Answer: Option D
4. One horse power is equal to

A. 746 watts

B. 748 watts

C. 756 watts

D. 736 watts

Answer: Option A

Explanation :Electrical equivalent of one horsepower is 746 watts in the International System of Units (SI), and the heat equivalent is 2,545 BTU (British Thermal Units) per hour.
5. Very small time intervals are accurately measured by—-

A. White dwarfs

B. Quartz clocks

C. Atomic clocks

D. Pulsars

Answer: Option C

Explanation :Atomic clocks are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, to control the wave frequency of television broadcasts, and in global navigation satellite systems such as GPS.

6. Decibel is the unit used for:

A. Speed of light

B. Intensity of heat

C. Intensity of sound

D. Radio wave frequency

Answer: Option C

Explanation :Decibel (dB), unit for expressing the ratio between two physical quantities, usually amounts of acoustic or electric power, or for measuring the relative loudness of sounds.
7. Newton is the unit of:

A. Force

B. Momentum

C. Acceleration due to gravity

D. Velocity

Answer: Option A

Explanation :The newton is the SI unit of force, and is the force which will accelerate one kilogram one metre per second squared. The symbol of the newton in SI is N.
8. Noise or Noise pollution measured in:

A. Phon

B. Deci

C. Decibel

D. Decimal

Answer: Option C

Explanation :decibel (dB), unit for expressing the ratio between two physical quantities, usually amounts of acoustic or electric power, or for measuring the relative loudness of sounds. One decibel (0.1 bel) equals 10 times the common logarithm of the power ratio.
9. Which layer protects earth from harmful rays of the Sun?

A. Ionosphere

B. Ozone layer

C. Troposphere

D. Magnetosphere

Answer: Option B

Explanation :The ozone layer or ozone shield is a region of Earth’s stratosphere that absorbs most of the Sun’s ultraviolet radiation. It contains a high concentration of ozone in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere.
10. Which is the absolute temperature scale?

A. Celsius

B. Fahrenheit

C. Kelvin

D. All of these

Answer: Option C

Explanation :Absolute temperature is used in application of the ideal gas law and many other laws of thermodynamics. A scale for absolute temperature with degree units the same as on the Celsius scale is known as the Kelvin scale; the absolute temperature scale using Fahrenheit degree units is the Rankine scale.
11. What are metal bearing rocks called?

A. Bitumen

B. Bauxite

C. Metalloids

D. Ores

Answer: Option D

Explanation :Ore is metal-bearing rock that can be mined, transported, processed, and sold at a profit. Although a broader definition includes nonmetallic rocks like rock salt and gypsum, most geologists classify these materials as industrial rocks and minerals.
12. The percentage of oxygen present in air is approximately-

A. 44%

B. 23%

C. 40%

D. 21%

Answer: Option D

Explanation :The air in Earth’s atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen. Air also has small amounts of lots of other gases, too, such as carbon dioxide, neon, and hydrogen.
13.Which one of the following is the petroleum wax?

A. Paraffin wax

B. Jonoba wax

C. Carnauba wax

D. Bees wax

Answer: Option A

Explanation :Paraffin wax is obtained from petroleum by dewaxing light lubricating oil stocks. It is used in candles, wax paper, polishes, cosmetics, and electrical insulators. It assists in extracting perfumes from flowers, forms a base for medical ointments, and supplies a waterproof coating for wood. In wood and paper matches, it helps to ignite the matchstick by supplying an easily vaporized hydrocarbon fuel.
14. What cause a moving body to resist a change in its state of motion?

A. Displacement

B. Acceleration

C. Inertia

D. Velocity

Answer: Option C

Explanation :Inertia: tendency of an object to resist changes in its velocity. An object at rest has zero velocity – and (in the absence of an unbalanced force) will remain with a zero velocity. Such an object will not change its state of motion (i.e., velocity) unless acted upon by an unbalanced force.
16. AIDS is caused by:

A. Bacteria

B. Fungus

C. Helminth

D. Virus

Answer: Option D

Explanation :Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV). By damaging your immune system, HIV interferes with your body’s ability to fight infection and disease.
18. The vast resources of unutilised natural gas can be used in the production of-

A. Graphite

B. Synthetic petroleum

C. Fertilisers

D. Carbide

Answer: Option C
19. Paper is manufactured by

A. Wood and resin

B. Wood, sodium and bleaching powder

C. Wood, calcium, hydrogen sulphide and resin.

D. Wood and bleaching powder

Answer: Option C

Explanation :Paper is a thin sheet material produced by mechanically and/or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed on the surface, followed by pressing and drying.
20. Gypsum is added to cement clinker to-

A. Increase the tensile strength of cement

B. Decrease the rate of setting of cement

C. Facilitate the formation of colloidal gel

D. Bind the particles of calcium silicate

Answer: Option A

Explanation :During cement manufacturing process upon cooling of clinker a small amount of gypsum is added during the final grinding process. Gypsum controls the setting of the cement and if not added the cement will set immediately leaving no time for concrete placing.
21. Soap is a mixture of sodium or potassium salts of

A. Dicarboxylic acids

B. Mono-carboxylic acids

C. Glycerol

D. Tricarboxylic acids

Answer: Option B
22. The type of glass used in making lenses and prisms is

A. Jena glass

B. Soft glass

C. Pyrex glass

D. Flint glass

Answer: Option D

Explanation :In the optical glass industry, flint glass is any highly refractive lead-containing glass used to make lenses and prisms. Because it absorbs most ultraviolet light but comparatively little visible light, it is also used for telescope lenses.
23. What are the soaps?

A. Salts of silicates

B. Mixture of glycerol and alcohols

C. Sodium or potassium salts of heavier fatty acids

D. Esters of heavy fatty acids

Answer: Option C

Explanation :Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are used as thickeners, components of some lubricants, and precursors to catalysts.
24. How does common salt help in separating soap from the solution after saponification?

A. By decreasing density of Soap

B. By decreasing solubility of Soap

C. By increasing density of Soap

D. By increasing solubility of Soap

Answer: Option B

Explanation :Common salt help in separating soap from the solution after saponification by decreasing solubility of soap.
25. In vulcanisation, natural rubber is heated with

A. Carbon

B. Silicon

C. Sulphur

D. Phosphorous

Answer: Option C

Explanation :Vulcanization is a chemical process in which the rubber is heated with sulphur, accelerator and activator at 140–160°C. The process involves the formation of cross-links between long rubber molecules so as to achieve improved elasticity, resilience, tensile strength, viscosity, hardness and weather resistance.
26. Deep blue colour is imparted to glass by the presence of

A. Cupric oxide

B. Nickel oxide

C. Cobalt oxide

D. Iron oxide

Answer: Option C

Explanation :Cobalt is a very intense glass colorant and very little is required to show a noticeable amount of colour. Colour of Cobalt glass is blue.
27. Glass is made of the mixture of:

A. Quartz and mica

B. Sand and silicates

C. Salt and quartz

D. Sand and salt

Answer: Option B
28. Which of the following is a protein?

A. Natural rubber

B. Starch

C. Cellulose

D. None of th.
29. Wood is the main raw material for the manufacture of—

A. Paint

B. Paper

C. Ink

D. Gun powder

Answer: Option B

Explanation : paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed on the surface, followed by pressing and drying
30. Rayon is chemically a

A. Cellulose

B. Pectin

C. Glucose

D. Amylase

Answer: Option A

Explanation :Rayon is chemically labelled cellulose acetate, which is a polymer of a semi-synthetic type. It is called semi-synthetic because it has a natural cellulose portion that in combination with acetate gives cellulose acetate (rayon).
31. Optical fibers are mainly used for which of the following?

A. Musical instruments

B. Food industry

C. Weaving

D. Communication

Answer: Option D

Explanation :Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data transfer rates) than electrical cables.
32. The major ingredient of leather is–

A. Collagen

B. Carbohydrate

C. Polymer

D. Nucleic acid

Answer: Option A

Explanation :Leather is a durable and flexible material created by tanning animal rawhide and skins. The major ingredient of leather is Collagen.
33. Which of the following is used for removing air bubbles from glass during its manufacture?

A. Arsenous oxide

B. Potassium carbonate

C. Soda ash

D. Feldspar

Answer: Option A

Explanation :Arsenous oxide is used for removing air bubbles from glass during its manufacture.Arsenous oxide was once used as a rodenticide and in sheep dips. It is no longer approved for use in most countries due to its toxicity to humans and the environment. Arsenous oxide is highly toxic to all mammals, is a carginogen, a reproduction toxin and highly corrosiive. It is quite soluble in aqueous solution but practically insoluble in most organic solvents. It is also toxic to most fauna and flora.

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