Discussion Forum

1)

An electron  collides with a hydrogen atom in its ground  state and excites it to n=3 state. The energy  given to the hydrogen atom in this inelastic  collision

(neglecting  the recoil of hydrogen  atom ) is

Answer:

Option B

Explanation:

 According to the question,

 Energy  given to hydrogen atom= Difference in energy level from $n_{1}=1$ to $n_{2}$=3  states

$=13.6\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right)=13.6\left(\frac{1}{1^{2}}-\frac{1}{3^{2}}\right)=13.6\left(1-\frac{1}{9}\right)$

 $=13.6 \times \frac{8}{9}=12.08$ ≈12.1 eV