Question

Assertion :Each principal level of quantum number ${}^{\prime }{n}^{\prime }$ contains a total of ${}^{\prime }{n}^{\prime }$ sub levels. Reason: Each orbital can hold two electrons and each sub level of quantum number ${}^{\prime }{l}^{\prime }$ contains a total of $(2l+1)$ orbitals.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

The main shell with the principal quantum number $n$ contains $n$ subshells.

For $n=1$, only one subshell (s) is present.
For $n=2$, two subshells (s and p) are present.
For $n=3$, three subshells (s, p, and d) are present.
For $n=4$, four subshells (s, p, d, and f ) are present.

Only two electrons can be filled in a given orbital.
The number of orbitals present in a sub-level of the quantum number $l$ is equal to $(2l+1)$.

Thus, the number of orbitals present in s, p, d, and f sub levels is equal to 1, 3, 5 and 7 respectively.