Question

The longest wavelength of ` He^(+)` in paschen series is "m", then shortest wavelenght of `Be^(+3)` in Pacchen series is( in terms of m):
A. `(5)/(36)m`
B. `(64)/(7)m`
C. `(53)/(8)m`
D. `(7)/(64)m`

Answer 1

Correct Answer - D
`(1)/(lambda_("longest"))`=`(1)/(m_(e))`=`RZ^(2)((1)/(3^(2))-(1)/(4^2))`=`(7Rxx4)/(16xx9)=(7)/(36)R`
`(1)/(lambda_("longest"))`=`RZ^(2)((1)/(3^(2)))`=`(4R)/(9)`
`(lambda_("longest"))`=`(7)/(64)m`