Question

Which of the following series of elements have nearly the same atomic radii?

• A. $F.Cl,Br,I$
• B. $Na,K,Rb,Cs$
• C. $Li,Be,B,C$
• D. $Fe,Co,Ni,Cu$

Answer 1

The correct option is D $Fe,Co,Ni,Cu$

These are transition metals with the $(n-1)d^{1-10}{ns}^{1-2}$ configuration. The atomic number and ionic radii of transition elements in a given series show a decreasing trend for the first five elements and then becomes almost constant for the next five elements.

Hence, option $D$ is correct.