Question

The energy required to excite the electron in the atom from $n=1$ to $n=2,$ , when the ionisation enthalpy of hydrogen atom is $1.312\times {10}^{6}J$ /mol will be (in the unit of ${10}^5$ ).

• A. 8.53
• B. 7.51
• C. $8.92$
• D. 9.86

Answer 1

Answer: (D)

$E_2=\frac{-1.312\times {10}^6\times {(1)}^2}{{(2)}^2}$ $\text{=-3}\text{.28 }\times \text{ 1}{\text{0}}^{\text{5}}\text{J/mol}$
${\text{E}}_{\text{1}}\text{=-1}\text{.312 }\times \text{ 1}{\text{0}}^{\text{6}}\text{J/mol}$
$\therefore$ $\Delta E=E_2-E_1$
$=-3.28\times {10}^6-(1.312\times {10}^6)$
$\text{= 9}\text{.84 }\times \text{ 1}{\text{0}}^{\text{5}}\text{J/mol}$