Question

The restriction of emission line spectrum for $H$-atom/$H$-like species is given by selection rule. For $H$-like species the transitions which do not follow the restrictions given below are forbidden.
Rules:$\Delta n=$any value; $\Delta l=\pm 1;$ $\Delta m=0,\pm 1$
According to this rule following transitions are not allowed:

• A. $4p$ to $3p$
• B. $4f$ to $3d$
• C. $4p$ to $3d$
• D. $4d$ to $3s$

Answer 1

Answer: (A), (D)

The correct options are
A $4d$ to $3s$
D $4p$ to $3p$

The restriction of emission line spectrum for $H$-atom/$H$-like species is given by selection rule. For $H$-like species the transitions which do not follow the restrictions given below are forbidden.
Rules:$\Delta n=$any value; $\Delta l=\pm 1;$ $\Delta m=0,\pm 1$
According to this rule following transitions are not allowed:
$4p$ to $3p$ $\Delta l=0$
$4d$ to $3s$$\Delta l=2$
According to this rule following transitions are allowed.
$4f$ to $3d$ $\Delta l=1$
$4p$ to $3d$ $\Delta l=1$