CAPF (AC) 2019 (Paper-1) (Question 1-50)

Total Questions: 50

31. When a longitudinal wave moves through a certain medium, the quantity which is transmitted through the medium is

Correct Answer: (b) energy only
Solution:

When a longitudinal wave moves through a certain medium only energy is transmitted through the medium.

In a longitudinal wave, the particles of the medium vibrate back and forth parallel to the direction in which the wave is travelling. Think about sound waves moving through air: the air molecules are pushed together (compression) and spread apart (rarefaction) along the path of the sound.

Consider a spring where you push one end. A compression travels along the spring. The coils of the spring vibrate forward and backward around their original positions, but they don't permanently move to the other end of the spring.
This brings us to the key point about waves:

  • The particles of the medium oscillate or vibrate about their equilibrium positions. They do not travel along with the wave itself.
  • The disturbance, which carries energy, is what moves through the medium.

So, while the medium's particles are essential for the wave to propagate (they transfer the disturbance from one particle to the next), the material itself is not transported over large distances by the wave. What is transported is the energy associated with the disturbance.

32. The number of neutrons inside the nucleus of the element Uranium-235 is

Correct Answer: (c) 143
Solution:

The Atomic number of Uranium - 235 is 92.

Number of neutrons = Mass number - Atomic number

Hence the number of neutrons will be 235 - 92 - 143

33. A snowboard pulled up by a tow rope travels at the rate of 5 m/s up a mountain. If 3000 watt of power is used, what force was applied to it?

Correct Answer: (c) 600 N
Solution:

Power = Work ÷ Time

Or, Power = Force × displacement ÷ Time

Or, Power = Force × Velocity

Or, Force = Power ÷  Velocity = 3000/5 = 600

Hence the force will be 600 N

34. Which one of the following is NOT true for an electromagnetic wave?

Correct Answer: (c) Electromagnetic wave is longitudinal
Solution:

An electromagnetic wave is not longitudinal but transverse in nature. It means the electric and magnetic fields oscillate in a plane that is perpendicular to the direction of propagation of the wave.

35. Which one of the following is NOT an electromagnetic wave?

Correct Answer: (c) Sound wave
Solution:

Sound waves are not electromagnetic wave. Electromagnetic waves can travel through a vacuum and transverse in nature which is not the property displayed by sound waves.

  • The electromagnetic waves are produced due to the vibration of an electric charge. A time varying electric field gives rise to a time varying magnetic field. The vice versais also true.
  • They can also be produced when high speed electrons enter into the target metal which has high atomic weight. EM waves are also produced when a radioactive nucleus de-excites.

36. Brilliance of diamond is due to

Correct Answer: (d) total internal reflection of light
Solution:

Brilliance of diamonds is due to total internal reflection of light. It occurs when the light rays travel from a more optically denser medium to a less optically denser medium and the angle of incidence is greater than the critical angle then the light is reflected back to the reflected back into the denser medium.

37. Which of the following conditions is/are essential for wheat cultivation?

1. Optimum temperature during growing period is around 30°C

2. A frost-free period of about 100 days

3. Light clay or heavy loam soil

Select the correct answer using the code given below :

Correct Answer: (c) 2 and 3 only
Solution:

The following conditions are essential for wheat cultivation:

  • Ideal temperature is between 10º- 15º C at time of souring and 21º - 26ºC at time of harvesting.
  • It requires brost free period of about 100 days.
  • It requires 50 - 75 cm of annual rainfall.
  • The most suitable soil is well drained fertile 100 mg soil and dayey soil.

38. Gwadar port is located in

Correct Answer: (a) Pakistan
Solution:

The Gwadar port is located on the South-western coast of Balochistan, Pakistan. It is important part of China Pakistan Economic Corridor and China's One Belt One Road project and Maritime Silk Road Project.

39. North-west part of the Indian peninsula was converted into a great centre of vulcanicity in

Correct Answer: (a) the end of Cretaceous period
Solution:

The north-west part of the Indian peninsula was converted into a great center of vulcanicity in the end of the Cretaceous period.
Cretaceous Period

  • In geologic time, the Cretaceous Period is the final of the Mesozoic Era's three eras.
  • The Cretaceous Period began 145.0 million years ago and ended 66 million years later; it came after the Jurassic Period and was replaced by the Paleogene Period.
  • The Cretaceous Period is the longest of the Phanerozoic Eon.
  • It spans 79 million years, which is more time than has passed since the extinction of the dinosaurs at the conclusion of the era.
  • The majority of Cretaceous rocks are not chalked, but the majority of chalks were deposited during the Cretaceous period.
  • They have not been distorted or eroded and are relatively close to the surface, many of these rocks reveal distinct and easily accessible characteristics of the time, as seen in the white cliffs surrounding the Strait of Dover between France and England.

40. What is the natural number n for which 3⁹ + 3¹² + 3¹⁵ + 3ᵐ is a perfect cube of an integer?

Correct Answer: (d) 14
Solution:

3⁹ + 3¹² + 3¹⁵ + 3ᵐ⁺⁹ = 3⁹ × (1 + 3³ + 3⁶ + 3ᵐ)

(where, m = n - 9 )

Since, 3⁹ is a cube of 3³ , let we find the value of 3ᵐ which will result in a cube for expression

(1 + 3³ + 3⁶ + 3ᵐ) = (1 + 27 + 729 + 3ᵐ)

When m = 1 ⇒ 757 + 3¹ = 760

This is not a cube.

When m = 2 ⇒ 757 + 3² = 766

This is not a cube.

When m = 3 ⇒ 757 + 3³ = 784

This is not a cube.

When n = 4 ⇒ 757 + 3⁴ = 838

This is not a cube.

When n = 5 ⇒ 757 + 3⁵ = 1000

This is (10)³

Hence, m = 5 ⇒ n = 9 + m = 14