Question

The energy (in eV) required to excite an electron from $n = 2$ to $n = 4$ state in hydrogen atom is

• A. + 2.55
• B. - 3.4
• C. - 0.85
• D. + 4.25

Answer 1

Answer: (A)

We know that,
$E_{n}=\frac{13.6}{n^{2}}$
According to question, the required energy is
$E =E_{2}-E_{4} $
$=\frac{13.6}{(2)^{2}}-\frac{13.6}{4^{2}}=\frac{13.6}{4}-\frac{13.6}{16} $
$=\frac{(13.6 \times 4)-13.6}{16}$
$=\frac{40.8}{16}=+2.55$