Question

Assertion (A) The third period in the periodic table contains $18$ electrons and not $8$ like $2^\text{nd}$ period.
Reason (R) In third period, filling of electron starts from $3 s^{1}$ and complete at $3 p^{6}$.

• A. Both $A$ and $R$ are correct; $R$ is the correct explanation of $A$.
• B. Both $A$ and $R$ are correct; and $R$ is not the correct explanation of $A$.
• C. $A$ is correct; $R$ is incorrect.
• D. $R$ is correct; $A$ is incorrect.

Answer 1

Answer: (D)

The third period have outer subshell containing maximum eight electrons and filling of electrons in $3^\text{rd}$ period starts from $3 s^{1}$ to $3 p^{6}$ as

So, number of elements $=$ eight in third period.
Thus, $R$ is correct but $A$ is incorrect.