Assertion (A) – In 3d transition elements, the expected decrease in atomic radius is observed from Sc to V, thereafter upto Cu, the atomic radius nearly remains the same.
Reason (R) – As we move from Sc to V, the added 3d electrons only partially shield the increased nuclear charge but upto Cu, the extra electron added to 3d sub-shell repel the 4s electrons and the slight increase in nuclear charge operated in opposite direction and it leads to constancy in atomic radii.
(a) Both (A) and (R) are correct and (R) explains (A).
(b) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.
