Question

The shortest and longest wave number in H spectrum of Lyman series is (R = Rydberg constant) :

• A. $\frac{3}{4}$R, R
• B. $\frac{1}{R}$, $\frac{4}{3}$, R
• C. R, $\frac{4}{3}$R
• D. R, $\frac{3}{4}$R

Answer 1

The correct option is A $\frac{3}{4}$R, R

As we know, $\frac{1}{\lambda }=R{Z}^2(\frac{1}{n_1^2}-\frac{1}{n_2^2})$

Shortest $v$ means shortest E and vice versa so when $n_1=1,n_2=2$,

$v=R(\frac{1}{1^2}-\frac{1}{2^2})=\frac{3}{4}R$

And highest v means when electron come from infinite to that orbit.

$v=R(\frac{1}{1^2}-\frac{1}{0})=R$