Nuclear Physics And Radioactivity Question 56

Question: In the nuclear fusion reaction $ _{1}^{2}H+ _{1}^{3}H\to _{2}^{4}He+n, $ given that the repulsive potential energy between the two nuclei is $ -7.7\times {{10}^{-14}}J $ , the temperature at which the gases must be heated to initiate the reaction is nearly [Boltzmann?s constant $ k=1.38\times {{10}^{-23}}J/K $ ] [AIEEE 2003]

Options:

A) $ 10^{9}K $

B) $ 10^{7}K $

C) $ 10^{5}K $

D) $ 10^{3}K $

Show Answer

Answer:

Correct Answer: A

Solution:

Kinetic energy of the molecules of a gas at a temp. T is $ \frac{3}{2}kT $
$ \therefore $ To initiate the reaction $ \frac{3}{2}kT=7.7\times {{10}^{-14}}J $
$ \Rightarrow \frac{3}{2}\times 1.38\times {{10}^{-23}}T=7.7\times {{10}^{-14}}\Rightarrow T=3.7\times 10^{9}K $ .