51. Which physical quantity is conserved during collision?
(1) Mass
(2) Momentum
(3) Time
(4) Length
Answer: (2) Momentum
Explanation: Law of conservation of linear momentum applies in collisions (in absence of external forces).
52. Which of the following confirms that the universe is not static but expanding?
(1) Red shift in the light coming from distant galaxies
(2) Blue shift in the light coming from distant galaxies
(3) Bending of light while passing near to the Black hole
(4) Constancy of velocity of light
Answer: (1) Red shift in the light coming from distant galaxies
Explanation: Hubble’s Law — Redshift proves galaxies are moving away → Universe is expanding.
53. Neutrino particle is emitted in the process of _______.
(1) α-decay
(2) β-decay
(3) γ-decay
(4) X-ray
Answer: (2) β-decay
Explanation: In beta decay, a neutron → proton + electron + antineutrino (or positron + neutrino in β⁺). A neutrino is emitted in the process of beta decay, specifically during beta-plus (
β+beta plus𝛽+) decay where a proton transforms into a neutron, and in electron capture. It is also emitted during beta-minus (
β−beta minus𝛽−) decay, but this process emits an antineutrino instead of a neutrino.
54. What is the effect of increase in temperature on viscosity of gases?
(1) Viscosity increases
(2) Viscosity decreases
(3) Viscosity remains constant
(4) Viscosity becomes negative
Answer: (1) Viscosity increases
Explanation: For gases, viscosity ∝ √T (temperature). As temperature increases, molecular momentum exchange increases → viscosity increases.(Opposite for liquids)
Q. 33
The Bengal Florican is neither a reptile nor an amphibian.
The leatherback sea turtle’s IUCN status is vulnerable.
The gharial and four-toed river terrapin are both critically endangered.
So no option is correct.
Yes.