They are covalent compounds of carbon and generally insoluble in water and readily soluble in organic solvent such as benzene, toluene, ether, chloroform etc...
Many of the organic compounds are inflammable (except CCI₄). They possess low boiling and melting points due to their covalent nature
Organic compounds are characterised by functional groups. A functional group is an atom or a specific combination of bonded atoms that react in a characteristic way, irrespective of the organic molecule in which it is present. In almost all the cases, the reaction of an organic compound takes place at the functional group. They exhibit isomerism which is a unique phenomenon.
Homologous series: Aseries of organic compounds each containing a characteric functional group and the successive members differ from each other in molecular formula by a CH₂ group is called homologous series. Eg.
Alkanes: Methane (CH₄), Ethane (C₂H₆), Propane(C₃H₈) etc.Alcohols: Methanol (CH₃OH), Ethanol (C₂H₅OH) Propanol (C₃H₇OH) etc..) Compounds of the homologous series are represented by a general formula Alkanes C_nH_2n+2, Alkenes C_nH_2n, Alkynes C_nHr_2n-2 and can be prepared by general methods. They show regular gradation in physicial properties but have almost similar chemical property.

Weight of an organic compound = 0.24 g
Weight of Mg₂P₂O₇ = 0.66 g = y
\( \% \mathrm{P} =\frac{62}{222} \times \frac{\mathrm{y}}{\mathrm{w}} \times 100 \)
\(=\frac{62}{222} \times \frac{0.66}{0.24} \times 100=76.80 \%\)

(w) = 0.185 g
(x) = 0.320 g
\(\% \mathrm{Br}=\frac{80}{188} \times \frac{b}{w} \times 100=\frac{80}{188} \times \frac{0.320}{0.185} \times 100=73.6 \%\)

Weight of the organic substance = 0.284 g
Weight of AgCl is = 0.287 g = a
\( \% \mathrm{Cl} =\frac{35.5}{143.5} \times \frac{\mathrm{a}}{\mathrm{w}} \times 100 \)
\(=\frac{35.5}{143.5} \times \frac{0.287}{0.284} \times 100=24.98 \% \)

i) Butan.- I - ol & Butan - 2 -ol are position isomers. - Position isomerism
ii) Butan -I -ol & 2-methyl propan - I - ol are chain isomers - Chainisomerism
iii) Butan -I - ol and I - methoxy propane are functional isomers - Functional isomerism
iv) 1 - methoxy Propane and ethoxy ethane and 2 - methoxy Propane are metamers - Metamerism

(i) They are covalent compounds of carbon and generally insoluble in water and readily soluble in organic solvent such as benzene, toluene, ether, chloroform, etc ...
(ii) Many of the organic compounds are inflammable  (except CCI₄).They possess low boiling and melting points due to their covalent nature.
(iii) Organic compounds are characterised by functional groups. A functional group is an atom or a specific combination of bonded atoms that react in a characteristic way, irrespective of the organic molecule in which it is present. In
almost all the cases, the reaction of an organic compound takes place at the functional group. They exhibit isomerism which is a unique phenomenon.
(iv) Homologous series: A series of organic compounds each containing a characteristic functional group and the successive members differ from each other in molecular formula by a CH₂ group is called homologous series.
Alkanes: Methane (CH₄) Ethane (C₂H₆)  Propane (C₃H₈) etc.

Partition Chromatography:
Paper chromatography (PC) is an example of partition chromatography. The same procedure is followed as in thin layer chromatography except that a strip of paper acts as an adsorbent is method involves continues differential portioning of  components of a mixture between stationary and mobile phase. In paper chromatography, a special quality paper known as chromatography paper is used. This paper act as a stationary phase.
A strip of chromatographic paper spotted at the base with the solution of the mixture is suspended in a suitable solvent which act as the mobile phase solvent rises up and flows over the spot. The paper selectively retains different components according to their different partition in the two phases where a chromatogram is developed. The spots of the separated colored compounds are visible at different heights from the position of initial spots on the chromatogram. The spots of the separated colorless compounds may be observed either under ultraviolent light or by the use of an appropriate spray reagent.

A known mass of the organic compound is heated with fuming HNO₃ and AgNO₃. C, H & S get oxidized to CO₂, H₂O & SO₂ and halogen combines with AgNO₃ to form a precipitate of silver halide.
\(X=\xrightarrow [ fum.HNO_{ 3 } ]{ AgNO_{ 3 } } AgX\downarrow \)
The precipitate of AgX is filtered, washed, dried and weighed. From the mass of AgX and the mass of the organic compound taken, percentage of halogens are calculated.
A known mass of the substance istaken along with fuming HNO₃ and AgNO, is taken in a clean carius tube. The open end of the Carius tube is sealed and placed in a irbn tube for 5 hours in the range at 530- 540 k Then the tube is allowed to cool and a small hole is made in the tube to allow gases produced to escape. The tube is broken and the ppt is filtered, washed, dried and weighed. From the mass of AgX obtained, percentage of halogen in the organic compound is calculated.
Weight of the organic compound : w g
Weight of AgCI precipitate = a g
Percentage of CI in w g = \(\left(\frac{35.5}{143.5} \times \frac{\mathrm{a}}{\mathrm{w}} \times 100\right) \%\)
organic compound
Let Weight of silver Bromide be 'b'g
Percentage of Br in w g = \(\left(\frac{80}{188} \times \frac{b}{w} \times 100\right) \%\) organic compound
Let Weight of silver Iodide be 'c'g
w g Organic compound gives c g AgI
Percentage of l in w g = \(\left(\frac{127}{235} \times \frac{c}{w} \times 100\right) \%\) organic compound.

Homologous series: A series of organic compounds each containing a characteric functional group and the successive' members differ from each other in molecular formula by a CH₂ group is called homologous series. Eg.
Alkanes : Methane (CH₄), Ethane (C₂H₆), Propane (C₃Hg) etc .
Alcohols: Methanol (CH₃OH), Ethanol (C₂H₅OH) Propanol (C₃H₇OH) etc ..)
Compounds of the homologous series are represented by a general formula Alkanes CnH_2n+2' Alkenes C_nH_2n, Alkynes C_nH_2n-2 and can be prepared by general methods. They show regular gradation in physical properties but have almost similar chemical property.

Aliphatic monohydric alcohol : R - OH