Assertion : In transition elements, radii of 5d series are virtually the same as those of the corresponding members of 4d series.
Reason : The filling of 4f orbitals before 5d orbitals results in regular decrease in atomic radii.

Options

A. If both (A) and (R) are correct and (R) is the correct explanation of(A).
B. If both (A) and (R) are correct, but(R) is not the correct explanation of (A).
C. If(A) is correct, but (R) is incorrect.
D. If both (A) and (R) are incorrect.

Answer

A

Explanation

Lanthanide contraction.