Which of the following transistions in hydrogen atom will require the highest amount of energy
 

The electron transition from n=1 to n=3 in hydrogen atom will require largest amount of energy.
The amount of energy is directly proportional to
$\left[\frac{1}{n_1^2}-\frac{1}{n_2^2}\right]$

This difference is maximum for the electron transition from n=1 to n=2

$\left[\frac{1}{1_{ }^2}-\frac{1}{3_{ }^2}\right]=0.89$