Target Exam

CUET

Subject

Physics

Chapter

Nuclei

Question:

The atomic mass of ${^{12}_{6}C}$ is 12.000000 u and that of ${^{13}_{6}C}$ is 13.003354 u. The energy required to remove a neutron from ${^{12}_{6}C}$ is

(Given: Mass of neutron is 1.008665u and 1 u = 931 MeV)

Options:

2.73 MeV

4.94 MeV

6.08 MeV

7.31 MeV

Correct Answer:

4.94 MeV

Explanation:

The correct answer is Option (2) → 4.94 MeV

Given:

Mass of $^{12}_6\text{C} = 12.000000\,\text{u}$

Mass of $^{13}_6\text{C} = 13.003354\,\text{u}$

Mass of neutron: $m_n = 1.008665\,\text{u}$

Conversion: $1\,\text{u} = 931\,\text{MeV}$

Energy required to remove a neutron from $^{13}_6\text{C}$:

Neutron separation energy $S_n = [m(^{12}\text{C}) + m_n - m(^{13}\text{C})] c^2$

$S_n = (12.000000 + 1.008665 - 13.003354)\,\text{u} \cdot 931\,\text{MeV/u}$

$S_n = (13.008665 - 13.003354)\,\text{u} \cdot 931 = 0.005311 \cdot 931 \approx 4.94\,\text{MeV}$

Answer: $S_n \approx 4.94\,\text{MeV}$