Question

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

• A. Both assertion and reason are true and reason is the correct explanation of assertion
• B. Both assertion and reason are true but reason is not the correct explanation of assertion
• C. Assertion is true but reason is false
• D. Both assertion and reason are false

Answer 1

Answer: (A)

Both assertion and reason are true and reason is the correct explanation of assertion

Answer 2

The wavelength in Balmer series is given by $\frac {1}{?}=R \bigg [\frac {1}{2^2}- \frac {1}{n^2} \bigg ], \, n=3,4,5,....$ $\frac {1}{?_{max}}=R\bigg [\frac {1}{2^2}- \frac {1}{3^2} \bigg ]$ $\frac {1}{?_{max}}=\frac {36}{5R}= \frac {36}{5 \times 1.097 \times 10^7}=6563 \mathring {A}$ and $\frac {1}{?_{min}}=R \bigg [\frac {1}{2^2}- \frac {1}{??2}\bigg ]$ $?_{min}= \frac {4}{R}= \frac {4}{1.097 \times 10^7}=3646 \mathring {A}$ The wavelength $6563 \, \mathring {A} \, and \, 3646 \, \mathring {A}$ lie in visible region. Therefore, Balmer series lies in visible region.