Chemistry MCQs for NEET — Practice Questions with Answers

When benzene reacts with chlorine (Cl₂) in the presence of light, it undergoes a free radical substitution reaction, leading to the formation of benzene hexachloride (C₆H₆Cl₆). This process involves the addition of six chlorine atoms to the benzene ring.

Benzene reacts with chlorine ($Cl_2$) in the presence of a catalyst such as ferric chloride ($FeCl_3$) to form chlorobenzene. The reaction is an example of electrophilic aromatic substitution where the benzene ring is substituted by a chlorine atom. The chemical equation for the reaction is: $$ \text{C}_6\text{H}_6 + \text{Cl}_2 \xrightarrow{\text{FeCl}_3} \text{C}_6\text{H}_5\text{Cl} + \text{HCl} $$

$ m - Directors \Rightarrow -NO_2 , -SO_3H , -COOH , -CN , CHO, -COR $

$ O–P Directors \Rightarrow CH_3 , -OH , -OR, -NH2 , - X (Halogen) $

Catalytic reduction of styrene involves the addition of hydrogen (hydrogenation) to the double bond in the presence of a catalyst like palladium, platinum, or nickel. This process converts styrene (C6H5-CH=CH2) to ethylbenzene (C6H5-CH2-CH3).

$ -COOC_2 H_5 $ m - Director

$ Bond length \alpha 1/ Bondorder there for bond length in$

When phenol (C6H5OH) is heated with zinc dust, it undergoes a reduction reaction where the hydroxyl group (-OH) is removed and replaced with a hydrogen atom, resulting in the formation of benzene (C6H6). The reaction is: \[ C_6H_5OH + Zn \rightarrow C_6H_6 + ZnO \]