MCQs of Nuclei

Nuclei MCQs

Showing 51 to 60 out of 138 Questions

51.

If the energy released in the fission of one nucleus is 200 MeV, then number of nuclei required per second in a power plant of 16 kW is _____ .

(a)	5 × 10¹⁴
(b)	5 × 10¹²
(c)	0.5 × 10¹²
(d)	0.5 × 10¹⁴

52.

A source of energy of 100 W is producing energy by fission of 1 kg {}^{235}U . How long can it keep generation of energy_____. (approx)

(a)	2.6 × 10⁴ yr
(b)	10⁶ sec
(c)	8.6 × 10⁷ sec
(d)	100 yr

53.

Which of the following is a neutron absorber ?

(a)	Pb
(b)	Ag
(c)	Cd
(d)	Cu

54.

200 MeV energy is liberated by nuclear fission of {}_{92}^{235}U . Fission rate of uranium nuclei in a reactor which delivers power of 5 kW .

(a)	1.56 × 10¹⁰ s^-1
(b)	1.56 × 10¹¹ s^-1
(c)	1.56 × 10¹⁰ s^-1
(d)	1.56 × 10¹⁷ s^-1

55.

The half-life of a radioactive isotope X is 50 years. It decays to another element Y which is stable. The two elements X and Y were found to be in the ratio of 1 : 15 in a sample of a given rock. The age of rock was estimated to be _____ .

(a)	100 years
(b)	150 years
(c)	200 years
(d)	250 years

56.

The half-life of a radioactive isotope 'X' is 20 years. It decays to another element 'Y' which is stable. The two elements 'X' and 'Y' were found to be in the ratio of 1 : 7 in a sample of a given rock. The age of rock was estimated to be _____ .

(a)	40 years
(b)	60 years
(c)	80 years
(d)	100 years

57.

A mixture consists of two radioactive materials A₁ and A₂ with half-lives of 20 s and 10 s respectively. Initially the mixture has 40 g of A₁ and 160 g of A₂. The amount of the two in the mixture will become equal after _____ .

(a)	60 s
(b)	80 s
(c)	20 s
(d)	40 s

58.

A radio isotope 'X' with a half-life 1.4 × 10⁹ years decays to 'Y' which is stable. A sample of the rock from a cave was found to contain 'X' and 'Y' in the ratio 1 : 7. The age of the rock is _____ .

(a)	1.96 × 10⁹ years
(b)	3.92 × 10⁹ years
(c)	4.20 × 10⁹ years
(d)	8.40 × 10⁹ years

59.

The half-life of a radioactive substance is 30 minutes. The time (in minutes) taken between 40 % decay and 85 % decay of the same radioactive substance is _____ .

(a)	30
(b)	45
(c)	60
(d)	15

60.

When a {}^{238}U nucleus originally at rest, decays by emitting an alpha particle having a speed' u' the recoil speed of the residual nucleus is_____.

(a)	$- \frac{4 u}{234}$
(b)	$\frac{4 u}{234}$
(c)	$- \frac{4 u}{238}$
(d)	$\frac{4 u}{238}$

Showing 51 to 60 out of 138 Questions