Question

An electronic transition in hydrogen atom results - in the formation of $Ha$ 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)

Energy of electron in $n ^{\text {th }}$ 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
$2 \rightarrow 1$
Therefore, energy of electron in the orbit $1$ and $2$ are:
$E _{1}=-313.6 \times\left(1 / 1^{2}\right)=-313.6 \,kCal / mol$
$E _{2}=-313.6 \times\left(1 / 2^{2}\right)=-78.4\, kCal / mol$