Question

An electronic transition in hydrogen atom results in the formation of the $H_{\alpha }$ line of hydrogen in Lyman series, the energies associated with the electron in each of the orbits involved in the transition (in $kcal$ ${mol}^{-1}$) are:

• A. $-313.6,-34.84$
• B. $-313.6,-78.4$
• C. $-78.4,-34.84$
• D. $-78.4,-19.6$

Answer 1

Answer: (B)

$-313.6,-78.4$

Energy of electron in $n^{th}$ an orbit in hydrogen atom in kCal/mol is given as:

$E_n=-313.6\times \left(1/n^2\right)kCal/mol$

$H_{\alpha }$ line in Lyman series of Hydrogen corresponds to the first line of transition from $2\to 1$

Therefore, energy of electron in the orbit 1 and 2 are:

$E_1=-313.6\times \left(1/1^2\right)=-313.6kCal/mol$

$E_2=-313.6\times \left(1/2^2\right)=-78.4kCal/mol$

Hence, option B is correct.