Absolute alcohol cannot be obtained by simple fractional distillation because

Pure C₂H₅OH is unstable
C₂H₅OH form hydrogen bonds with water
Boiling point of C₂H₅OH is very close to that of water
Constant boiling azeotropic mixture is formed with water

Solution

Absolute alcohol cannot be obtained by simple fractional distillation because a Constant boiling azeotropic mixture is formed. It is impossible to get pure ethanol by distiling any mixture of ethanol and water containing less than 95.6% of ethanol. This particular mixture of ethanol and water boils as if it were a pure liquid. It has a constant boiling point, and the vapour composition is exactly the same as the liquid.

Solution

Electron withdrawing group (–NO₂) increases acidity while electron releasing group (–CH₃, –H) decreases acidity. Also effect will be more if functional group present at para position then ortho and then meta.

The optical inactivity due to internal compensation can be exhibited by :

dextro-tartaric acid
laevo-tartaric acid
racemic-tartaric acid
meso-tartaric acid

Solution

Optical inactivity due to internal compensation is exhibited by meso-tartaric acid. Option(d) is correct.

The replacement of chlorine of chloro benzene to give phenol requires drastic conditions, but the chlorine of 2,4-dinitrochlorobenzene is readily replaced since,

nitro groups make the aromatic ring electron rich atortho/para positions
nitro groups withdraw electrons from the meta position of the aromatic ring
nitro groups donate electrons at meta position
nitro groups withdraw electrons from ortho/parapositions of the aromatic ring

Solution

The shape of methyl carban ion is similar to that of –

BF₃
NH₃
methyl free radical
methyl carbocation

Solution

Methyl carbanion is sp³ hybridised, with three bond pairs and one lone pair same is the case with NH₃.

Chromatography is a valuable method for the separation,isolation, purification and identification of the constituents of a mixture and it is based on general principle of

phase rule
phase distribution
inter phase separation
phase operation

Which of the following pairs represent electrophiles?

AlCl₃,H₂O
SO₃, \(NO_{2}^{+}\)
BF₃, H₂O
NH₃, SO₃

Solution

Electrophiles are electron deficient or positively charged species.

An asymmetric carbon atom is that in which :

three similar and one dissimilar groups
two similar and two dissimilar groups
all the different groups
none of the above

Solution

An asymmetric carbon atom is that in which all different groups are attached with carbon. Option (c) is correct.

The number of ? and ?bonds in a molecule of acetonitrile are respectively

2, 5
3,4
4,3
5,2

Solution

In Kjeldahl’s method for the estimation of nitrogen, the foumula used is

%N = \(\frac{1.4VW}{N}\)
%N = \(\frac{1.4VW}{V}\)
%N = \(\frac{VNW}{1.8}\)
%N = \(\frac{1.4VN}{W}\)

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