Classification of elements and Periodicity in properties MCQs for NEET — Chemistry Questions with Answers

In a carbon atom, the electronic configuration is $1s^2 2s^2 2p^2$. The 2p orbital has two unpaired electrons. Therefore, the number of unpaired electrons in a carbon atom is 2.

inert pair effect is most prominent in Pb because from top to bottom due to increase in number of shells.

$ CCl_4 + H_2O \rightarrow$ No reaction d - orbital absent in carbon atom

$ C + 2H_2SO_4 \rightarrow CO_2 + 2H_2O + 2SO_2 $ Here carbon is oxidized to $ CO_2 \& H_2SO_4 is reduced to SO_2 $

Silica on heating with carbon at elevated temp gives carborandum (Silicon Carbide) $ SiO_2 + 3C \rightarrow [] { { \triangle } } SiC + 2CO_2 $ Carborandum is very hard substance

Organic acids dissolve lead in presence of oxygen $ Pb + 2CH_3COOH + {1/2} O_2 \rightarrow Pb (CH_3COO)2 + H_2O $

Lead (Pb) commonly exhibits +2 and +4 oxidation states. The +2 oxidation state is more stable for lead due to the inert pair effect, where the 6s electrons are less available for bonding. Thus, the correct oxidation states of lead are +2 and +4.

Quartz is a three-dimensional network silicate. In quartz, each silicon atom is bonded to four oxygen atoms in a tetrahedral structure, forming a continuous three-dimensional network. This structure contributes to the hardness and stability of quartz.

Phosphorus does not form stable diatomic molecules. Instead, it exists in forms such as white phosphorus (P4) or red phosphorus, which are more stable. In contrast, iodine (I2), nitrogen (N2), and oxygen (O2) form stable diatomic molecules.