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)

Ionisation energy of carbon group follows the order :

$C>Si>Ge>Sn<Pb$

$I{E}_{Pb}>I{E}_{Sn}$ because of poor shielding effect of $d\&f-$ electrons.