Modern Physics Ques 190
Passage Based Questions
Passage
The mass of a nucleus ${ } _Z^{A} X$ is less that the sum of the masses of $(A-Z)$ number of neutrons and $Z$ number of protons in the nucleus. The energy equivalent to the corresponding mass difference is known as the binding energy of the nucleus. A heavy nucleus of mass $M$ can break into two light nuclei of masses $m _1$ and $m _2$ only if $\left(m _1+m _2\right)<M$. Also two light nuclei of masses $m _3$ and $m _4$ can undergo complete fusion and form a heavy nucleus of mass $M^{\prime}$ only if $\left(m _3+m _4\right)>M^{\prime}$. The masses of some neutral atoms are given in the table below
(2013 Adv.)
| ${ } _1^{1} H$ | $1.007825 u$ | ${ } _1^{2} H$ | $2.014102 u$ |
|---|---|---|---|
| ${ } _3^{6} Li$ | $6.01513 u$ | ${ } _3^{7} Li$ | $7.016004 u$ |
| ${ } _{64}^{152} Gd$ | $151.919803 u$ | ${ } _{82}^{206} Pb$ | $205.974455 u$ |
| ${ } _1^{3} H$ | $3.016050 u$ | ${ } _2^{4} He$ | $4.002603 u$ |
| ${ } _{30}^{70} Zn$ | $69.925325 u$ | ${ } _{34}^{82} Se$ | $81.916709 u$ |
- The correct statement is
(a) The nucleus ${ } _3^{6} Li$ can emit an alpha particle.
(b) The nucleus ${ } _{84}^{210}$ Po can emit a proton.
(c) Deuteron and alpha particle can undergo complete fusion.
(d) The nuclei ${ } _{30}^{70} Zn$ and ${ } _{34}^{82} Se$ can undergo complete fusion.
Show Answer
Answer:
Correct Answer: 190.(c)
Solution:
Formula:
- (a) ${ } _3 Li^{7} \rightarrow{ } _2 He^{4}+{ } _1 H^{3}$
$ \begin{aligned} \Delta m & =\left[M _{Li}-M _{He}-M _{H^{3}}\right] \\ & =[6.01513-4.002603-3.016050] \\ & =-1.003523 u \end{aligned} $
$\Delta m$ is negative so reaction is not possible.
(b) ${ } _{84} Po^{210} \rightarrow{ } _{83} Bi^{209}+{ } _1 P^{1}$
$\Delta m$ is negative so reaction is not possible.
(c) ${ } _1 H^{2} \rightarrow{ } _2 He^{4}+{ } _3 Li^{6}$
$\Delta m$ is positive so reaction is possible.
(d) ${ } _{30} Zn^{70}+{ } _{34} Se^{82} \rightarrow{ } _{64} Gd^{152}$
$\Delta m$ is positive so reaction is not possible.
BETA
