Question

What is the wave number of 4th line in Balmer series of hydrogen spectrum? $(R=1,09,677c{m}^{-1})$

• A. $24,630c{m}^{-1}$
• B. $24,360c{m}^{-1}$
• C. $24,730c{m}^{-1}$
• D. $24,372c{m}^{-1}$

Answer 1

Answer: (D)

$\bar{v}=R\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)$ For Balmer series $n_1=2$ and for 4th line in Balmer series $n_2=6$ $\because$ $R=109677c{m}^{-1}$ $\bar{v}=109677\left(\frac{1}{4}-\frac{1}{36}\right)$ $=109677\left(\frac{1}{4}-\frac{1}{36}\right)$ $\bar{v}=24,372c{m}^{-1}$