Question

The energy absorbed by each molecule $\left(A_{2}\right)$ of a substance is $4.4 \times 10^{-19}\,J$ and bond energy per molecule is $4.0 \times 10^{-19}\,J$. The kinetic energy of the molecule per atom (in eV) will be

• A. $1.37\,eV$
• B. $1.24\,eV $
• C. $0.249\,eV$
• D. $0.124\,eV$

Answer 1

Answer: (D)

Energy absorbed by each molecule $= 4.4 \times 10^{-19}\,J$
Energy required to break the bond $= 4.0 \times 10^{-19}\,J$
Remaining energy which gets converted to kinetic energy
$= (4.4 \times 10^{-19} - 4.0 \times 10^{-19})\,J$
$= 0.4 \times 10^{-19}\,J$ per molecule Kinetic energy per atom
$ = 0.2 \times 10^{-19}\,J$ or $2 \times 10^{-20}\,J$
Also $1\,J = 6.24 \times 10^{18}\, eV$
$\therefore K.E$. per atom $ = 0.124\, eV$