It is essential to purify an organic compound. The method used for purification depends upon nature of compound and impurity present in it. The common methods to purify a solid is sublimation and crystallisation. Crystallisation is most common method applicable to most of solid organic compounds. Liquids are purified by simple distillation, fractional distillation, distillation under reduced pressure, steam distillation. Differential extraction is used to extract organic compound from aqueous solution. Chromatography is used to separate coloured substances from plants. Column chromatography, thin layer chromatography and partition chromatography are types of chromatography used for isolation and purification of organic compounds.
(a) Which method is used to purify camphor?
(b) How is unwanted colour from organic compounds removed?
(c) How is chloroform (Boiling point 334 K) and aniline (b.pt. 457 K) are separated? Why?
(d) Which is condensed first in fractionating column, vapours of higher boiling point liquid or lower boiling point liquid?
(e) How is glycerol purified?
(f) How is Aniline purified? Why?
(g) How are o-nitrophenol and p-nitrophenol separated? Why?

The order of decreasing priority of some functional groups is \(-\mathrm{COOH},-\mathrm{SO}_{3} \mathrm{H},-\mathrm{COOR},-\mathrm{COCl},-\mathrm{CONH}_{2}\), 

Observe the table based on different functional groups and their respective prefix and suffix given below and answer the questions as follow.

Functional Group	Prefix	Suffix
Alkane	-	- ane
Alkane	-	- ene
Alkane	-	- yne
-x	Halo (chloro, bromo, iodo)	-
-OH	Hydroxy	- ol
	Aldo or formyl	- al
	Oxo	- one
\(-\mathrm{C} \equiv \mathrm{N}\)	Cyano	nitrile
-ROR	Alkoxy	ether
-COOH	Carboxy	- oic acid
-COOR	Alkoxy carbonyl	- oate
-NH2	Amino	- amine
-NO2	Nitro	-
-CONH2	Carbamoyl or Amido	- amide
-COX	Halo formyl	- oyl halide
-SO3H	Sulpho	sulphonic acid

(a) Write IUPAC Dame of HOCH₂ -(CH₂ )₃-CH₂COCH₃ .
(b) What is IUPAC Dame of CH₂ =CH-CH₂Br. Give reason.
(c) What is IUPAC name of 
 (i) 
 
(ii) CH₂ =CH-CH=CH₂ 
(d) Write structural formula of 6-methyl ectan-s-ol.
(e) Write IUPAC name of
(i) 

(ii) 

(f) Write IUPAC name of 

(g) Write structural formula of cyclohex-2-en-1-ol.

Organic compounds are formed by covalent bonding. The nature of covalent bonding can described with the help of hybridisation, sp, Sp² and sp³. The structure and reactivity depends upon type of bonds present in organic compounds. Organic compound can be represented by various structural formulae, Wedge and Dash formula is 3-D representation. Organic compounds can be classified on the basis of functional groups. Organic reactions mechanism are based on structure of substrate and the attacking reagent.
The intermediate formed can be free radical, carbocation, carbanion or carbene. The attacking reagent can be electrophile or nucleophile. The inductive, electromeric, resonance and hyper conjugative effect may help in polarisation of covalent bond. Organic reactions may be regarded as substitution, addition, elimination and rearrangement, oxidation and reduction reaction.
After the compound is obtained in pure state, qualitative analysis helps to detect elements present in organic compounds whereas quantitative analysis helps to find percentage of various elements. Dumas and Kjeldahl method help to determine percentage of nitrogen, Carius method for halogens and sulphur. Carbon and hydrogen are estimated by the amount of CO₂ and H₂Oformed. Phosphorus estimation is done by oxidising it to H₃ PO₄, sulphur to H₂ SO₄ , The percentage of oxygen is determined by taking the difference of 100 and percentage of all elements. Empirical formula gives simple ratios of elements whereas molecular formula gives exact number of atoms of each element present in a compound.
(a) What are free radicals?
(b) Write the order of stability of carbocation.
(c) An organic compounds has 8% sulphur. What is minimum molar mass of compound?
(d) If C is 75%, H = 25%, what is molecular formula of compound?
(e) In estimation of sulphur, which compound of sulphur is formed?
(f) f Lassaigne extract of organic compound give blood-red colour with FeCI₃, what does it show?
(g) Why should we add HNO₃ to Lassaigne extract before testing for halogens.