Mock Test-5 (Paper-1) (Question 51-100)

Total Questions: 50

21. The symbol of SI unit of inductance is H. It stands for

Correct Answer: (c) Henry
Solution:The henry (H) is the Standard International (SI) unit of inductance. Reduced to base SI units, one henry is the equivalent of one kilogram meter squared per second squared per ampere squared (kg m² s⁻² A⁻²).

22. A ball balanced on a vertical rod is an example of

Correct Answer: (b) unstable equilibrium
Solution:A ball balanced on a vertical rod is an example of unstable equilibrium.

23. The apparent weight of a steel sphere immersed in various liquids is measured using a spring balance. The greatest reading is obtained for the liquid

Correct Answer: (c) in which the sphere was submerged deepest
Solution:When a body immersed in a liquid, then the apparent weight of the body depends upon the densities of the liquids and volume of the portion of the solid immersed in liquid. So, the apparent weight of a steel sphere will be greatest for the liquid in which the sphere was submerged deepest.

24. Which one of the following statements about the refractive index of a material medium with respect to air is correct?

Correct Answer: (d) It is always greater than one
Solution:Refractive index of a medium with respect to air is the ratio of the velocity of light in air to the velocity of the light in the medium. It is also the ratio of the refractive index of the medium with respect to vacuum to the refractive index of air with respect to vacuum.

25. Optical fibre works on the principle of

Correct Answer: (a) total internal reflection
Solution:An optical fibre is a thin, flexible, transparent fibre that acts as a waveguide or "light pipe" to transmit light between the two ends of the fibre. An optical fibre transmits light along its axis, by the process of total internal reflection.

When light traveling in a dense medium hits a boundary at an angle larger than the "critical angle" for the boundary, the light will be completely reflected. This effect is used in optical fibres to confine light in the core.

26. Which one of the following statements is NOT correct?

Correct Answer: (c) The velocity of sound in air decreases as the humidity increases.
Solution:The velocity of sound in air is determined by the air itself and is not dependent upon the amplitude, frequency, or wavelength of the sound. The velocity of sound c depends on the temperature of air and not on the air pressure.

Thus, velocity of sound in air increases with temperature and remains unaffected with increase of pressure. Therefore, statements 1, 2 and 4 are right. Only statement 3 is wrong.

The only other factor that has any effect on the speed of sound in air is the amount of humidity in the air. An increase in the amount of humidity in the air increases the speed by a small amount. The velocity of sound in air increases as the humidity increases.

27. The nucleus of a singly ionized carbon atom contains

Correct Answer: (a) 6 protons and 6 neutrons
Solution:The charged carbon atom in a carbocation is a "sextet", i.e. it has only six electrons in its outer valence shell instead of the eight valence electrons that ensures maximum stability (octet rule). Therefore carbocations are often reactive, seeking to fill the octet of valence electrons as well as regain a neutral charge.

28. .

Assertion (A): Aluminium foil cannot be used in a particle scattering experiment.

Reason (R): Aluminium is highly malleable metal.

Correct Answer: (b) Both A and R are correct but R is not the correct reason for А.
Solution:Both assertion and reason is correct. Gold has a capacity of being rolled to extremely thin foil i.e. it is most maleable metal. So, it is used in ascattering experiment.

29. Hydrogen bomb is based on the principle of

Correct Answer: (b) uncontrolled fusion reaction
Solution:Hydrogen bomb was discovered by the American scientist in 1952. It is based on the reaction of nuclear fusion. It is based on uncontrolled chain reaction.

30. The chemical name of baking soda is

Correct Answer: (b) NaHCO₃
Solution:Baking soda or baking powder has various chemical names like sodium bicarbonate (Na2CO3), bicarbonate of soda, sodium hydrogen carbonate (NaHCO3), etc. It is also called sodium bicarb or simply bicarb. Its main chemical formula is NaHCO3, and it's prepared industrially by Solvay process.