Question

Assertion: The basic strength of oxides and hydroxides of lanthanoids decrease with increase in atomic number.

Reason: The size of cation of lanthanoids increases with increase in atomic number.

विकल्प

• If both Assertion and Reason are CORRECT and Reason is the CORRECT explanation of the Assertion.

• If both Assertion and Reason are CORRECT but Reason is not the CORRECT explanation of the Assertion.

• If Assertion is CORRECT but Reason is INCORRECT.

• If Assertion is INCORRECT but Reason is CORRECT.

Answer 1

If Assertion is CORRECT but Reason is INCORRECT.

Explanation:

The basic strength of oxides and hydroxides of lanthanoids decreases with an increase in atomic number due to lanthanoid contraction, which causes a decrease in ionic size. However, the reason is incorrect because the size of lanthanoid cations actually decreases, not increases, with an increase in atomic number.