Question

Which of the following pairs do not show the inert-pair effect ?

• A. $Tl$ and $Pb$
• B. $Sn$ and $Bi$
• C. $Sn$ and $Pb$
• D. $Si$ and $Ge$

Answer 1

The correct option is D $Si$ and $Ge$

Inert pair effect is shown by ${13}^{\text{th}}$ to ${15}^{\text{th}}$ group and lower $5^{\text{th}}$, $6^{\text{th}}$ period elements due to lanthanide contractions.
The inert pair effect is shown by $Tl$, $Pb$ and $Sn$ due to which, the lower oxidation state is more stable than the higher oxidation state again, they are all lower periodic elements.
But $Si$ and $Ge$, being higher up in the periodic table, does not show inert pair effect.