Question

The ratio of Rydbergs constant for helium to the Rydbergs constant for hydrogen is :

• A. 1 : 2
• B. 1 : 4
• C. 4 : 1
• D. 1 : 1

Answer 1

Answer: (C)

Rydbergs constant is given by
$R=\frac{m{Z}^2{e}^4}{8{\epsilon }_0^{2}c{h}^3}$
For hydrogen $Z=1$,
for helium $Z=2$
$\therefore \frac{R_{He}}{R_H}=\frac{{(2)}^2}{{(1)}^2}=\frac{4}{1}$