English (Part – B) (General studies) NDA/NA SOLVED PAPER 2019 (II) (51 to 100)

Total Questions: 50

11. Which one of the following statements about water is not true?

Correct Answer: (d) Water is a non-polar molecule.
Solution:

The option (d) contains incorrect statement. Water is a polar molecule in which central oxygen atom is sp³ -hybridised.
Out of four sp³ -hybrid orbit, two for σ bond with H-atom and rest two are occupied by lone pair of electrons.
Thus, due to V-shaped structure of H₂O is a polar molecule (µ = 1840).

12. A sample of ‘soft soap’ contains:

Correct Answer: (b) potassium
Solution:

Soaps are the sodium or potassium salts of long chain fatty acid (RCOONa). e.g. stearic acid (C₁₇H₃₅COOH), oleic acid (C₁₇H₃₃COOH) and palmitic acid (C₁₅H₃₁COOH). Therefore, a sample of soft soap contains sodium or potassium. Thus, the option (b) is correct.

13. If an object moves at a non-zero constant acceleration for a certain interval of time, then the distance it covers in that time:

Correct Answer: (a) depends on its initial velocity
Solution:

If object moving with non-zero constant acceleration, then the displacement covered by it, is given by equation
s = ut + 1/2at²
where, s = displacement, u = initial velocity, a = acceleration and t = time. Hence, from above equation, displacement is dependent to initial velocity. Distance covered is a non-linear curve of time.

14. A solid disc and a solid sphere have the same mass and same radius. Which one has the higher moment of inertia about its centre of mass?

Correct Answer: (a) The disc
Solution:

15. Two substances of densities ρ₁ and ρ₂ are mixed in equal volume and their relative density is 4. When they are mixed in equal masses, relative density is 3. The values of ρ₁ and ρ₂ respectively, are

Correct Answer: (a) 6, 2
Solution:

16. A car starts from Bengaluru, goes 50 km in a straight line towards South, immediately turns around and returns to Bengaluru. The time taken for this round trip is 2h. The magnitude of the average velocity of the car for this round trip

Correct Answer: (a) is zero
Solution:

17. “The sum of emf’s and potential differences around a closed loop equals zero” is a consequence of

Correct Answer: (d) conservation of energy
Solution:

It is Kirchhoff’s second law also known as loop’s law.
i.e.        ΣE = iR
It is based on conservation of energy, since work done in a closed path is zero.

18. A student measures certain lengths using a meter scale having least count equal to 1 mm.

Which one of the following measurement is more precise?

Correct Answer: (c) 0.925 mm
Solution:Using instrument of higher precision improving experimental techniques, etc., we can reduce the least count error. Here, option (c) 0.925 mm is more precise than other

19. If the work done on the system or by the system is zero, then which one of the following statement for a gas kept at a certain temperature is correct?

Correct Answer: (a) Change in internal energy of the system is equal to flow of the heat in or out of the system.
Solution:

20. Consider the following part of an electric circuit.

Correct Answer: (b) 15/7 Ω
Solution: