The correct statement is , The mass of a nucleus is less than the sum of the masses of number of neutrons and number of protons in the nucleus. [2013]

Question

The mass of a nucleus ${}_{Z}^{A}X$ is less than 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 $(m_{1} + m_{2}) < M$ . Also two light nuclei of masses $m_{3}$ and $m_{4}$ can undergo complete fusion and form a heavy nucleus of mass $M'$ only if $(m_{3} + m_{4}) > M'$ . The masses of some neutral atoms are given in the table below:

Q. The correct statement is [2013]

Smart Achievers · Accepted Answer

(3)

In case of (3) only, mass defect $(Δ m)$ is positive. In all other cases (1), (2) and (4), $Δ m$ is negative.

Hence, deuteron and $α$ -particle can undergo complete fusion.

Solution

1 The nucleus ${}_{3}^{6}{Li}$ can emit an alpha particle

2 The nucleus ${}_{84}^{210}{Po}$ can emit a proton

3 Deuteron and alpha particle can undergo complete fusion

4 The nuclei ${}_{30}^{70}{Zn}$ and ${}_{34}^{82}{Se}$ can undergo complete fusion

Ans.
(3)

In case of (3) only, mass defect $(Δ m)$ is positive. In all other cases (1), (2) and (4), $Δ m$ is negative.

Hence, deuteron and $α$ -particle can undergo complete fusion.

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Solution

1 The nucleus Li36 can emit an alpha particle

2 The nucleus Po84210 can emit a proton