Question

When hydrogen atom is in its first excited level, its radius is _______ of the Bohr radius.

• A. Twice
• B. $4$ times
• C. Same
• D. Half

Answer 1

The correct option is B $4$ times

When hydrogen atom is in its first excited level,

$n=2$

The radius of hydrogen atom in the first excited level is

$r=n^2{r}_0$

$r=(2{)}^2{r}_0=4r_0$

where, $r_0=$ Bohr's radius.

The correct option is B.