Question

Which among the following elements have lowest value of $I{E}_1$?

• A. Pb
• B. Sn
• C. Si
• D. C

Answer 1

Answer: (B)

Sn

The ${IE}_1$ value decreases down the group due to increasing atomic size. However due to poor shielding of f-electrons, the ${IE}_1$ of $6^{th}$ period elements is higher than ${IE}_1$ of $5^{th}$ period elements of p-block. Thus the lowest ${IE}_1$ among given options is of ${}^{\prime }S{n}^{\prime }$.