The energy absorbed by each molecule $\left(\mathrm{A}_2\right)$ of a substance is $4.4 \times 10^{-19}…

The energy absorbed by each molecule $\left(\mathrm{A}_2\right)$ of a substance is $4.4 \times 10^{-19} \mathrm{~J}$ and bond energy per molecule is $4.0 \times 10^{-19} \mathrm{~J}$. The kinetic energy of the molecule per atom will be :
  1. $4.0 \times 10^{-20} \mathrm{~J}$
  2. $2.0 \times 10^{-20} \mathrm{~J}$
  3. $2.2 \times 10^{-19} \mathrm{~J}$
  4. $4 \times 10^{-19} \mathrm{~J}$

Solution

$\begin{gathered} \mathrm{KE}=4.4 \times 10^{-19}-4.0 \times 10^{-19} \\ \mathrm{KE} / \text { molecule }=0.4 \times 10^{-19} \\ \mathrm{KE} / \text { atom }=\frac{0.4 \times 10^{-19}}{2} \\ =2 \times 10^{-20} \mathrm{~J} \end{gathered}$

Asked in: NEET 2009 (Mains)

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