MCQs of Nuclei

Nuclei MCQs

Showing 21 to 30 out of 138 Questions

21.

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

22.

In the process of forming helium from hydrogen, the mass defect is 0.5%. What is the energy produced when helium is formed from 1kg hydrogen ? [ 1 kWH = 36 x 105 J ]

(a)	1.25 kWH
(b)	$1.25 \times 10^{6} k W H$
(c)	$1.25 \times 10^{8} kWH$
(d)	$1.25 \times 10^{4} kWH$

23.

A r a d i o a c t i v e e l e m e n t X d i s i n t e g r a t e s s u c c e s s i v e l y a s u n d e r : X \overset{α}{\to} X_{1} \overset{β^{-}}{\to} X_{2} \overset{α}{\to} X_{3} \overset{γ}{\to} X_{4} . I f t h e a t o m i c n u m b e r a n d t h e a t o m i c m a s s n u m b e r o f X a r e r e s p e c t i v e l y 72 a n d 180, w h a t a r e t h e c o r r e s p o n d i n g v a l u e s f o r X_{4} ?

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

24.

The half life of a radioactive element X is equal to the average life of other element Y. Initially number of atoms in both of them is same. Then,

(a)	initially rates of disintegration of X and Y would be equal
(b)	X and Y both disintegrate at the same rate, always.
(c)	initially rate of disintegration of Y would be greater than that of X
(d)	initially rate of disintegration of X would be greater than that of Y.

25.

The elements X₁ and X₂ have decay constants10λ and λ respectively. If initially they have equal number of nuclei, then after what time would the ratio of numbers of nuclei of X₁ and X₂ be

\frac{1}{e}

(a)	$\frac{1}{10 λ}$
(b)	$\frac{1}{11 λ}$
(c)	$\frac{11}{10 λ}$
(d)	$\frac{1}{9 λ}$

26.

The radius of the nucleus {}_{8}^{16}O is 3 \times 10^{- 15} m . The density of this nucleus will be_____\frac{kg}{m^{3}}

(a)	2.35 × 10^-17
(b)	2.35 × 10¹⁵
(c)	2.35 × 10¹⁷
(d)	2.35 × 10^-15

27.

The graph of \log (\frac{R}{R_{0}}) versus A (R = radius of a nucleus and A = mass number) is_____.

(a)	a circle
(b)	an ellipse
(c)	a parabola
(d)	a straight line

28.

Two nucleons are separated by a distance of 10^-15 m. The net force between them is F₁, if both are neutrons, F₂ if both are protons and F₃ if one is a proton and other is a neutron. In such a case _____ .

(a)	F₂ > F₁ > F₃
(b)	F₁ = F₂ = F₃
(c)	F₁ = F₂ > F₃
(d)	F₁ = F₃ > F₂

29.

The mass of proton is 1.0073 u and that of neutron is 1.0087 u . The binding energy of {}_{2}^{4}{He} is_____. (Given : Mass of helium nucleus = 4.0015 u)

(a)	2.84 MeV
(b)	28.4 MeV
(c)	284 MeV
(d)	0.284 MeV

30.

The mass defect in a particular nuclear is 0.3 g. The amount of energy liberated in kilowatt hours. (velocity of light = 3 × 10⁸ m/s)

(a)	1.5 × 10⁶
(b)	2.5 × 10⁶
(c)	3 × 10⁴
(d)	7.5 × 10⁶

Showing 21 to 30 out of 138 Questions