Chemistry MCQs for NEET — Practice Questions with Answers

(c) HCHO is gas at room temperature. Its aqueous solution called formalin (42% HCHO+8% CH₃OH) is used as preservative for biological specimens.

(b) Glucose reduces Fehling's solution.

Acetals are diethers derived from aldehydes or ketones by the addition of two molecules of alcohol with the elimination of one molecule of water. They are formed by reacting an aldehyde or ketone with an alcohol in the presence of an acid catalyst.

(b) (CH₃)₂CHOH $\stackrel{\left[\mathrm{O}\right]}{\to }$(CH₃)₂CO

(c) R₂CCl₂ $\stackrel{\mathrm{HOH}}{\to }$R₂C(OH)₂ $\to$R₂CO

Ketones are prepared by Oppenaauer's oxidation, which involves the oxidation of a secondary alcohol using a mixture of aluminum isopropoxide and acetone. This reaction is used to convert a secondary alcohol into a ketone by removing hydrogen from the alcohol and adding it to the acetone.

(a) Cl₂ reacts with CH₃CHO, CH₃COCH₃ and C₆H₅CHO to give CCl₃CHO,CCl₃COCH₃ and C₆H₅COCl, respectively.

(c) A characteristic test for carbonyl gp., red salt is formed.

(c) Hydrocarbons are oxidised to aldehydes because only these two are present in atmosphere.

(b) $—\underset{\mathrm{H}}{\underset{|}{\mathrm{C}}}=\mathrm{O}$