Question

The size of Mo is very similar to:

• A. $La$
• B. $Hf$
• C. $Ta$
• D. $W$

Answer 1

The correct option is D $W$

Due to poor shielding effect of 4f electrons the nucleus experiences more effective nuclear charge and results in contraction which is known as Lanthanide contraction. Due to lanthanide contraction 5th and 6th period transition series elements have similar size. Thus size of Mo is similar to that of W.