NEET Practice Questions (MCQs) with Answers & Solutions

(a) Molar mass of compound  is 46 which is of ethanol. It also gives iodoform test.                               

(b) Secondary amine is reacted with benzene sulphonyl chloride to form solid compound which is insoluble in alkali

its 2 degree alcohol, which on oxidation gives ketone, and since product will be propanone , so it will give +ve iodoform reaction.

To differentiate between 1,1-dichloroethane and 1,2-dichloroethane, the test involves first treating with aqueous KOH and then with 2,4-dinitrophenylhydrazine (2,4-DNP). 1,2-dichloroethane will give a positive test (orange precipitate) while 1,1-dichloroethane will not react.

Dehydrohalogenation is the process of eliminating hydrogen and halogen atoms from an alkyl halide to form an alkene. The reagents commonly used for this process are alcoholic KOH, sodium amide (NaNH2), and sodium ethoxide (C2H5ONa). Therefore, the correct option is 'all of these'.

The given reaction is an example of addition of hydrogen halide (HX) to an alkene (ethene). According to Markovnikov's rule, the hydrogen atom gets added to the carbon with fewer hydrogen atoms, and the halide (X) gets added to the carbon with more hydrogen atoms. Hence, the product is CH2=CHCHO.

Zn dust is used for dehalogenation,

${\mathrm{CH}}_2\mathrm{X}·{\mathrm{CH}}_2\mathrm{X}\underset{\mathrm{alc}.}{\overset{\mathrm{Zn} \mathrm{dust}}{\to }}{\mathrm{CH}}_2={\mathrm{CH}}_2$

To prepare 3-chloroaniline from benzene, the best sequence is: nitration (to introduce -NO2 group), chlorination (to introduce -Cl group at 3-position), and finally reduction (to convert -NO2 to -NH2). Nitration is carried out first as the nitro group is a strong deactivating group.

(a) A white precipitate with am. AgNO₃ confirms the presence of terminal alkyne.