Isomerism exhibited by acetic acid and methyl formate is:
1. Functional
2. Chain
3. Geometrical
4. Central 

An isomer of ethanol is-

The pair of structures that does not represent isomers is:

1.		2.
3.		4.

The pair that represents chain isomers is- 

The number of primary amines of the formula ${\mathrm{C}}_4{\mathrm{H}}_{11}\mathrm{N}$ are :