Give a brief description of the principles of the following techniques taking an example in each case. 
(a) Crystallisation    (b) Distillation      
(c) Chromatography

Discuss the principle of estimation of halogens, sulphur and phosphorus present in an organic compound.

Why is nitric acid added to sodium extract before adding silver nitrate for testing halogens?

In the organic compound CH₂ = CH – CH₂ – CH₂ – C ≡ CH, the pair of hybridised
orbitals involved in the formation of: C₂ – C₃ bond is:
(a) sp – sp²
(b) sp – sp³
(c) sp² – sp³
(d) sp³ – sp³

Presence of nitrogen in which among the following compounds can not be detected by Lassaigne method?

• Hydrazine

• Aniline

• p-toluidine

• Picric acid

The hottest region of Bunsen flame shown in the figure below is:

• region 2

• region 3

• region 4

• region 4

297.

The distillation technique most suited for separating glycerol from spent-lye in the soap industry is:

• fractional distillation

• steam distillation

• distillation under reduced pressure

• distillation under reduced pressure

For which of the following molecule significant μ≠ 0?

• only a

• a and b

• Only c

• Only c

Which branched chain isomer of the hydrocarbon with molecular mass 72u gives only one isomer of mono substituted alkyl halide?

• Tertiary butyl chloride

• Neopentane

• Isohexane

• Isohexane

Identify the compound that exhibits tautomerism

• 2-Butene

• Lactic acid

• 2-Pentanone

• 2-Pentanone