Question

If the energy absorbed by each $X_2$ molecule of a gas is $35$ x ${10}^{-19}J$ and the bond energy of $X_2$ is $180.6kJmo{l}^{-1}$ then the kinetic energy per atom will be

• A. $2.5$ x ${10}^{-19}J$
• B. $5.0$ x ${10}^{-20}J$
• C. $2.5$ x ${10}^{-20}J$
• D. $1.5$ x ${10}^{-19}J$

Answer 1

Answer: (C)

$2.5$ x ${10}^{-20}J$

Energy absorbed by $1$ molecule of $X_2$

Energy of Board discrimination for a molecule $=\frac{180.6\times {10}^{3}T}{6.022\times {10}^{23}}$

$=30\times {10}^{-20}J=3\times {10}^{-19}J$

$E=E_0+KE$

$\to 3.5\times {10}^{-19}=3\times {10}^{-19}+KE$

$KE$ of molecule $=0.3\times {10}^{-19}J=5\times {10}^{-20}J$.

$KE$ of atom $=\frac{5\times {10}^{-20}}{2}=2.5\times {10}^{-20}$