Given the value of Rydberg constant is `10^(7)m^(-1)`, the waves number of the lest line of the Balmer series in hydrogen spectrum will be:

Options

A. `0.5xx10^(7) m^(-1)`
B. `0.25xx10^(7) m^(-1)`
C. `2.5xx10^(7) m^(-1)`
D. `0.025xx10^(4) m^(-1)`

Answer

B

Explanation

Given , Rydberg constant, `R=10^(7)m^(-1)`
`:.` for last line in Balmer series `n_(2)-oo,n_(1)=2`
As we know that,
`(1)/(lambda)=R((1)/(n_(1)^(2))-(1)/(n_(2)^(2)))rArr(1)/(lambda)=10^(7)((1)/(2^(2))-(1)/(oo))`
`barv=(1)/(lambda)=(10^(7))/(4)=0.25xx10^(7)m^(-1)`