Question

Assertion :Balmer series lies in the visible region of the electromagnetic spectrum. Reason: $\frac{1}{\lambda }=R[\frac{1}{2^2}-\frac{1}{n^2}]$, where $n=3,4,5$.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

Wavelength is Balmer series is, $\frac{1}{\lambda }=R[\frac{1}{2^2}-\frac{1}{n^2}];\frac{1}{{\lambda }_{max}}=R[\frac{1}{2^2}-\frac{1}{3^2}]$
or ${\lambda }_{max}=\frac{36}{5R}=\frac{36}{5\times 1.097\times {10}^7}=6563\stackrel{\circ }{A}$
$1/{\lambda }_{min}=R[\frac{1}{2^2}-\frac{1}{{\infty }^2}]$
or ${\lambda }_{min}=\frac{4}{R}=\frac{4}{1.097\times {19}^7}=3646\stackrel{\circ }{A}$
So it lies in the visible region.