Question

When a hydrogen atom is in its first excited level, its radius is

• A. four times its ground state radius
• B. twice times its ground state radius
• C. same times its ground state radius
• D. half times its ground state radius.

Answer 1

The correct option is A four times its ground state radius

$R=\frac{R_0{n}^2}{z}$

Radius in ground state$=\frac{R_0}{z}$

Radius in first excited state$=\frac{R_0\times 4}{z}$

$(\because n=2)$

Hence, radius of first excited state is four times the radius in ground state