Question

The degeneracy of $H-atom$ in a shell is $9$.The value of principle quantum number (n) for the shell is ?

• A. $3$
• B. $9$
• C. $1$
• D. None of these

Answer 1

Answer: (A)

$3$

Degeneracy of the energy levels of the hydrogen atom $=n^2$

where,

n = principal quantum no.

Given that degeneracy of H−atom in a shell is 9.

$\therefore 9=n^2$

$\Rightarrow n=3$

Hence, the value of principal quantum number (n) for the shell is 3.