Atoms & Nuclei

JEE Main level, single correct, medium

195 of 239

Question 195 of 239

The atomic mass of C126C126 is 12.000000u12.000000u and that of C136C136 is 13.003354u13.003354u. The required energy to remove a neutron from C136C136, if mass of neutron is 1.008665u1.008665u, will be:

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Answer: (C) 4.95MeV4.95MeV

Given the nuclear reaction is
C136+Energy→C126+n10C136+Energy\rightarrow C126+n10
The mass defect for the above reaction can be calculated as follows:
Δm=[(12.000000+1.008665)−13.003354]u=−0.00531u\begin{matrix}\Delta m & = & \left[(12.000000+1.008665)-13.003354\right]u \\ & = & -0.00531u\end{matrix}
Hence, the energy required is given by
E=0.00531×931.5MeV=4.95MeV\begin{matrix}E & = & 0.00531\times 931.5MeV \\ & = & 4.95MeV\end{matrix}

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