Question

In which of the following pairs, the difference between the covalent radii of two metals is maximum?

• A. $K,Ca$
• B. $Mn,Fe$
• C. $Co,Ni$
• D. $Cr,Mn$

Answer 1

The correct option is A $K,Ca$

Potassium is an alkali metal and Calcium is an alkaline metal
whereas others are transition metals.
Covalent radii decrease on moving from left to right.
On moving from left to right, an electron is added which should increase the radii. Nuclear charge also increases from left to right whose effect predominates and atomic radii remains constant in transition elements.