Question

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

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

Answer 1

The correct option is A $+2.55$

Energy required to excite an electron from $n_1=2$ to $n_2=4$ state, $\Delta E=13.6(\frac{1}{n_1^2}-\frac{1}{n_2^2})$

$\therefore$ $\Delta E=13.6(\frac{1}{2^2}-\frac{1}{4^2})$ $eV$

Or $\Delta E=+2.55$ $eV$

As higher state have more energy than the lower states, thus an energy is given to the atom to excite.