JEE Main 2022 — Structure Of Atom Question with Solution

The order of increasing energy of electrons in an atom can generally be determined using the principal quantum number ($n$) and the azimuthal quantum number ($l$). The energy can be compared using the rule: the higher the $(n+l)$ value, the higher the energy. If two electrons have the same $(n+l)$ value, the electron with the higher $n$ value has the higher energy.

Analyze each electron's quantum numbers:

A. $$n=3,l=2\Rightarrow n+l=3+2=5$$

B. $$n=4,l=1\Rightarrow n+l=4+1=5$$

C. $$n=4,l=2\Rightarrow n+l=4+2=6$$

D. $$n=3,l=1\Rightarrow n+l=3+1=4$$

Comparing the values of $(n+l)$ and the principal quantum number $n$:

D: $n+l=4$, and $n=3$.

A and B: $n+l=5$, but A has $n=3$ while B has $n=4$. Therefore, A has a slightly lower energy than B.

C: $n+l=6$.

Thus, the correct order of increasing energy is:

$$D<A<B<C$$

Therefore, Option B is correct.