1
MCQ (Single Correct Answer)

AIPMT 2011 Prelims

The Lassaigne's extract is boiled with conc. HNO3 while testing for halogens. By doing so it
A
decomposes Na2S and NaCN, formed
B
helps in the precipitation of AgCl
C
increases the solubility product of AgCl
D
increases the concentration of N$$_3^ - $$ ions

Explanation

In case of Lassaigne’s test of halogens, it is necessary to remove NaCN and Na2S from the sodium extract, if nitrogen and sulphur are present. This is done by boiling the sodium extract with conc. HNO3.

NaCN + HNO3 $$ \to $$ NaNO3 + HCN $$ \uparrow $$

Na2S + 2HNO3 $$ \to $$ 2NaNO3 + H2S $$ \uparrow $$
2
MCQ (Single Correct Answer)

AIPMT 2011 Prelims

Which one is a nucleophilic substitution reaction among the following ?
A
B
C
D

Explanation

Because of high electronegativities of the halogen atom, the carbon halogen (C – X) is highly polarised covalent bond. Thus, the carbon atom of the C – X bond becomes a good site for attack by nucleophiles (electron rich species). Nucleophilic substitution reactions are the most common reactions of alkyl halides.
3
MCQ (Single Correct Answer)

AIPMT 2011 Prelims

Which one of the following is most reactive towards electrophilic reagent?
A
B
C
D

Explanation

+R effect of -OH group is greater than of -OCH3 group. That is why it is highly reactive towards electrophilic substitutions.
4
MCQ (Single Correct Answer)

AIPMT 2011 Prelims

The correct IUPAC name for the compound is

A
4-ethyl-3-propylhex-1-ene
B
3-ethyl-4-ethenylheptane
C
3-ethyl-4-propylhex-5-ene
D
3-(1 -ethylpropyl)hex- 1 -ene.

Explanation


4-ethyl-3-propylhex-1-ene

EXAM MAP

Joint Entrance Examination

JEE Advanced JEE Main

Medical

NEET

Graduate Aptitude Test in Engineering

GATE CE GATE ECE GATE ME GATE IN GATE EE GATE CSE GATE PI