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1

AIPMT 2012 Prelims

MCQ (Single Correct Answer)
Which nomenclature is not according to IUPAC system?
A
B
C
D

Explanation

In IUPAC nomenclature, preference is given to multiple bond than halogen substituent.
2

AIPMT 2011 Mains

MCQ (Single Correct Answer)
The IUPAC name of the following compound is

A
trans-2-chloro-3-iodo-2-pentene
B
cis-3-iodo-4-chloro-3-pentane
C
trans-3-iodo-4-chloro-3-pentene
D
cis-2-chloro -3-iodo-2-pentene.

Explanation



$$ \therefore $$ IUPAC name is trans-2-chloro-3-iodo-2-pentene.
3

AIPMT 2011 Mains

MCQ (Single Correct Answer)
Which of the following compounds undergoes nucleophilic substitution reaction most easily?
A
B
C
D

Explanation

Electron withdrawing group like -NO2 facilitates nucleophilic substitution reaction in chlorobenzene.
4

AIPMT 2011 Prelims

MCQ (Single Correct Answer)
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 $$ \uparrow $$

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