Halkoarenes & Haloarenes MCQs for NEET — Chemistry Questions with Answers

The NCERT text explicitly states, 'When a haloalkane with $\beta$-hydrogen atom is heated with alcoholic solution of potassium hydroxide, there is elimination of hydrogen atom from $\beta$-carbon and a halogen atom from the $\alpha$-carbon atom.' This confirms the necessity of a $\beta$-hydrogen. They typically form alkenes, can be unimolecular (E1) or bimolecular (E2), and are favored by higher temperatures and strong bases.

The context states: 'Thionyl chloride is preferred because in this reaction alkyl halide is formed along with gases SO2 and HCl. The two gaseous products are escapable, hence, the reaction gives pure alkyl halides.'

The context mentions: 'The reactions of primary and secondary alcohols with HCl require the presence of a catalyst, ZnCl2.'

The context states: 'With tertiary alcohols, the reaction is conducted by simply shaking the alcohol with concentrated HCl at room temperature.'

The context states: 'Alkyl iodides are often prepared by the reaction of alkyl chlorides/bromides with NaI in dry acetone. This reaction is known as Finkelstein reaction.'

The context explains: 'NaCl or NaBr thus formed is precipitated in dry acetone. It facilitates the forward reaction according to Le Chatelier’s Principle.'

The context lists: 'AgF, Hg2F2, CoF2 or SbF3' as metallic fluorides used in Swarts reaction. NaF is not mentioned.

The context specifies: 'Aryl chlorides and bromides can be easily prepared by electrophilic substitution of arenes with chlorine and bromine respectively in the presence of Lewis acid catalysts like iron or iron(III) chloride.'

The context states: 'Fluoro compounds are not prepared by this method due to high reactivity of fluorine.'

The context mentions: 'Replacement of the diazonium group by iodine does not require the presence of cuprous halide and is done simply by shaking the diazonium salt with potassium iodide.'