Question

Quantum numbers for some electrons are given below
A: $n=4,l=1$
B: $n=4,l=0$
C: $n=3,l=2$
D: $n=3,l=1$
The correct increasing order of energy of electrons

• A. $A<B<C<D$
• B. $D<C<B<A$
• C. $D<B<C<A$
• D. $C<B<A<D$

Answer 1

Answer: (C)

Energy $=(n+l)$
$A=n=4l=1=4+1=5$
$B=n=4l=0=4+0=4$
$C=n=3l=2=3+2=5$
$D=n=3l=1=3+1=4$
According to Pauli exclusion principle
(1) Larger the $(n+l)$; larer will be energy
(2) Same value of $(n+l)$; smaller $n$; more will be energy
$\therefore D<B<C<A$