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. $1.37eV$
• B. $1.24eV$
• C. $0.249eV$
• D. $0.124eV$

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 $1J=6.24\times 10^{18}eV$
$\therefore K.E$. per atom $=0.124eV$