Question

The sub energy level having minimum energy is
A. 3d
B. 5p
C. 4s
D. 4p

Answer 1

Hint: The electrons in an atom revolves around the nucleus in a particular shell i.e. K, L, M, N……….The first shell can accommodate $2$ electrons. Second and third shells contain $8,8$electrons respectively. Further, the fourth and fifth shells contain $18,18$ electrons and so on. After then the shells are subdivided into the atomic orbitals i.e. s, p, d, f. s can accommodate two electrons, p contains 6 and d & f contains $10,14$ electrons respectively.

Complete step by step answer:
The atomic orbitals of an atom fill with electrons according to Afbau principle.
Afbau principle: - According to this principle, the electrons are filled into atomic orbitals in the increasing order of their energy. Increasing order of atomic orbital is written as 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p and so on.
The first atomic orbital having minimum energy & then further atomic orbital slightly higher energy than first atomic orbital and so on.
According to Afbau principle the solution of the given statement is $4s$ i.e. option ‘C’ is correct.

So, the correct answer is “Option C”.

Additional Information:
Atomic orbital: - n atomic orbital may be defined as the three-dimensional space around the nucleus within which the probability of finding an electron of given energy is maximum. Atomic orbitals are divided into four types s p d f.
S-orbital can accommodate two electrons. The shape of s orbital is spherical. Discovery of finding the electron belonging to s orbital of any main shell is found to be identical in all directions at a given distance from the nucleus that is symmetrical around the nucleus.
P-orbital can accommodate 6 electrons. The shape of P orbital is dumbbell. The probability of finding the electron is the maximum into two lobes on the opposite sides of the nucleus.
d orbital can accommodate 10 electrons. Similarly the f block can accommodate the 14 electrons in its orbital.

Note:
 To solve such a kind of statement, the knowledge of atomic orbital and their types must be known. One should know the Afbau principle & increasing order of energy levels. An orbital contains maximum two electrons having opposite spins according to Pauli Exclusion principle. There are maximum \[\left( \text{2l}+\text{1} \right)\]orbitals for a given subshell as the value of l for ‘s’ subshell is zero so it contains 1 orbital only i.e. maximum two electrons.