Question

Assertion (A) Sixth and seventh periods in the periodic table contains $14$ elements.
Reason (R) In the periodic table $14$ elements each of sixth [from $Z=58$ to $Z=71$ ] and seventh periods [from $Z=90$ to $Z=103$ ] respectively are known as lanthanoids and actinoids.

• 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)

Sixth period contains $32$ elements and seventh period is incomplete and like sixth, the period would have $32$ elements.
Thus, $R$ is correct but $A$ is incorrect.