CAPF (AC) 2022 (Paper-1) (Question 1-50)

Total Questions: 50

21. Which one of the following is not the unit of pressure?

(a) pascal (Pa)
(b) N/(m²)
(c) J/(m²)
(d) bar

Correct Answer: (c) J/(m²)

Solution:Pascal is the SI unit of Pressure. Newtons/Square Meter is a unit that shows how the pascal unit is derived from other SI units. Pressure is defined as Force/Area and the SI unit for Force is newtons (N) and the SI unit for Area is Sq Meters (m ^ 2) 1 newton per square metre equals 1 pascal. The unit of pressure in the SI system is the pascal (Pa), defined as a force of one Newton per square meter. J / (m ^ 2) is the unit of Surface Tension.

22. Which one of the following materials cannot be used to make a convex lens?

(a) Aluminium
(b) Glass
(c) Sapphire
(d) Water

Correct Answer: (a) Aluminium

Solution:Alumunium cannot be used to make a convex lens. The property of a lens is that it allows light to pass through it. So, water, glass, plastic and sapphire allow the light to pass through them so, these can be used to make a lens.

23. The optical phenomenon responsible for the blue colour of sky is

(a) dispersion
(b) reflection
(c) refraction
(d) scattering

Correct Answer: (d) scattering

Solution:The Optical phenomenon responsible for the blue colour of sky is scattering of light. Blue light is scattered more than the other colours due to shorter wavelength.

When white light is passed through a glass prism it splits into its spectrum of colours (in order violet, indigo, blue, green, yellow, orange and red) and this process of white light splitting into its constituent colours is termed as dispersion.
The change in direction of a wave, while passing from one medium to another is known as refraction.
A reflection is an image that you can see in a mirror or in glass or water.

24. The electrical device used for converting mechanical energy into electrical energy is called

(a) voltmeter
(b) ammeter
(c) motor
(d) generator

Correct Answer: (d) generator

Solution:

The electrical device used for converting mechanical energy into electrical energy is called Generator.
A voltmeter is an instrument used for measuring electric potential difference between two points in an electric circuit. It is connected in paralle.
An ammeter is a measuring instrument used to measure the current in a circuit.
An electric motor is an electrical machine that converts electrical energy into mechanical energy.

25. The magnitude of focal length of a concave lens is 2 m. What is the power of the lens?

(a) +0.5 dioptre
(b) - 0.5 dioptre
(c) +2.0 dioptre
(d) - 1.0 dioptre

Correct Answer: (b) - 0.5 dioptre

Solution:The magnitude of focal length of a concave lens is 2m then the power of the lens will be -0.5 dioptre, because Power of lens = (1/Focal length) concave lenses have a negative power because their focal length is negative.

26. All the time of short circuit, the current in on electric circuit

(a) becomes zero
(b) remains same
(c) increases sharply
(d) decreases sharply

Correct Answer: (c) increases sharply

Solution:At the time of short circuit, the current in an electric circuit increases sharply.

Because short circuit, lets current for travelling along the unintended path with less or no electrical impedance.

27. If the linear momentum of a moving object changes by two times, then its kinetic energy will change by a factor of

(a) 2
(b) 4
(c) 6
(d) 8

Correct Answer: (b) 4

Solution:From momentum (P) kinetic energy (K)relation If momentum doubled then velocity also must have been doubled (as there is no change in mass).

linear momentum = MV

Kinetic energy = 1/2 MV²

hence new kinetic energy (K₂) = 1/2m(2V²)

= 1/2 × 4M V²

Hence, K₂ = 4K₁

28. Which one of the following oxides reacts with both acid and base?

(a) Aluminium oxide
(b) Calcium oxide
(c) Sodium oxide
(d) Potassium oxide

Correct Answer: (a) Aluminium oxide

Solution:Aluminium Oxide is one of the oxides reacts with both acid and base.

Some metal oxides, such as aluminum oxide, zinc oxide, etc., show both acidic as well as basic behavior. Such metal oxides can react with both acids as well as bases to produce salts and water. Metal oxides of this category are known as amphoteric oxides.

An acid is a substance that forms hydrogen ions H+ when dissolved in water.

A base is a substance that forms hydroxide ions OH-when dissolved in water.

29. Which of the following makes bread soft and spongy when baking soda is added?

(a) Sodium salt of acid
(b) NaHCO₃
(c) CO₂
(d) H₂O

Correct Answer: (c) CO₂

Solution:The release of carbon dioxide during fermentation makes the bread soft and fluffy.

Sodium bicarbonate, commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO₃.

It is a salt composed of a sodium cation and a bicarbonate anion.

Uses of baking soda -

In preparation of baking powder.
In making cold drinks.
As a laboratory reagent.
In manufacture of fire extinguishers.
As an antacid to decrease the acidity of stomach.

30. The average age of father and elder son is 35 years, the average age of father and younger son is 32 years and the average age of the two sons is 17 years. What is the average age of the father and his two sons?

(a) 30 years
(b) 27 years
(c) 28 years
(d) 29 years

Correct Answer: (c) 28 years