MCQs of Nuclei

Nuclei MCQs

Showing 81 to 90 out of 138 Questions

81.

During the life time of a radioactive element as time passes the number of its nuclei decreases and along with that _____ .

(a)	activity and λ go on decreasing
(b)	activity and λ go on increasing
(c)	activity decreases but λ remains constant
(d)	activity decreases but λ increase

82.

Half-life of a radioactive element is 5 min. At the end of 20 min. Its _____ % quantity will remain undisintegrated.

(a)	93.73
(b)	75
(c)	25
(d)	6.25

83.

By the disintegration of {}_{94}{Pu}^{241} the element which is produced is also radioactive and disintegrates . In such a series total 8 α - particles and 5 β - particles are emitted and then the process stops . Which is the final element produced ?

(a)	${}_{83}^{209}{Bi}$
(b)	${}_{82}^{209}{Pb}$
(c)	${}_{83}^{214}{Bi}$
(d)	${}_{82}^{214}{Pb}$

84.

If the half-lives of a radioactive element for α-decay and β-decay are 4 yr and 12 yr respectively, what percent would its total activity be of its initial activity after 12 yr ?

(a)	50
(b)	25
(c)	12.5
(d)	6.25

85.

If {}_{13}^{27}{Al} is a stable nucleus, what should be emitted from {}_{13}^{27}{Al} nucleus ?

(a)	α-particle
(b)	β^--particle
(c)	proton
(d)	β⁺-particle

86.

1 mole of an element emitting α-particles is placed in a vessel which stores them. Half life of that element is 5 hr. How long would it take for 4.515 × 10²³ α-particles to be stored in that vessel ?

(a)	4.515 hr
(b)	9.030 hr
(c)	10 hr
(d)	20 hr

87.

In the radioactive transformation X \overset{α}{\to} X_{1} \overset{β^{-}}{\to} X_{2} \overset{β^{-}}{\to} X_{3} Which two are isotopes ?

(a)	X and X₁
(b)	X and X₃
(c)	X₁ and X₂
(d)	X₂ and X₃

88.

Half life of a radioactive element X is 3 hr. It transforms to form a stable element Y. After the birth of X, at time t, the ratio of the nuclei of X and Y is 1 : 15, What is the value of t ?

(a)	12 hr
(b)	6 hr
(c)	24 hr
(d)	45 hr

89.

A radioactive element X disintegrates successively as under : X \overset{α}{\to} X_{1} \overset{β^{-}}{\to} X_{2} \overset{α}{\to} X_{3} \overset{γ}{\to} X_{4} If the atomic number and the atomic mass number of X are respectively 72 and 180, what are the corresponding values for X_{4} ?

(a)	69, 176
(b)	69, 172
(c)	71, 176
(d)	71, 172

90.

1 amu = _____ .

(a)	1 kg
(b)	1 g
(c)	the mass of ₆C¹²
(d)	12^th part of mass of atom of a ₆C¹²

Showing 81 to 90 out of 138 Questions