Find the `D.U.` and give the possible structures of following compounds `:`
a. `C_(7)H_(7)CL` that gives blcak soot on burning ?
b. `C_(3)H_(6)O`
c. `C_(3)H_(5)N`
d. `CH_(4)O_(3)S`

Explanation

`C_(7)H_(7)CLimplies C_(7)H_(7+1)=C_(7)H_(8)`
`i.` `D.U.=((2n_(C)+2)-n_(H))/(2)=((2xx7+2)-8)/(2)=4^(@)`
`ii` `C:H~~1:1`. It is an aromatic compound containing benzene ring whose `D.U.=4^(@)`. Black soot is given by the aromatic compound.
`iii` The compound may be one of those that are given below, having six `C` atoms in the benzene ring, one `C` atom extra, and one `(CI)` group.
Four isomeric structures are possible `:`
`1.`
`2.`
`b.` `C_(3)H_(6)OimpliesC_(3)H_(6)`
`i` `D.U.=((2xx3+2)-6)/(2)=1^(@)`
`ii` It may contain a carbonyl group or one `(C=C)`, bond with `(-OH)` group or a ring with `(-OH)` group.
`iii.` The compound may be `:`
`1.`
` 2.` `(` Prop `-1` en`-2-`ol`)`
`3.` Functional isomer of ketone is aldehyde
`(` Propanel `)` or `(` Propionaldehyde `)`
Tautomerisation `(1,3-` shift of `sigma-` and `pi-` bond `)`
`4.` `(`Prop `-1-`en`-2-`ol `)`
`5.` `(` Cyclopropan `-1-`ol `)`
Five isomerica structures are possibile.
`C_(3)H_(5)NimpliesC_(3)H_(5-1)=C_(3)H_(4)`
` D.U. =((2xx3+2)-4)/(2)=2^(@)`
It may contain `:`
`i` A cyanide group `(-C-=N)implies2 D.U.` and its functional isomer isocynaide.
The compound may be, `e.g.,`
`{:(1.,CH_(3)-CH_(2)-CH-=N,2.,CH_(3)-CH_(2)-Nunderset(rarr)(=)C),(," Propane nitrile",," Ethyl isocyanide"),(," or",," or"),(," Ethyl cyanide",," Ethyl carbylamine"):}`
`ii` It may contain one `(C-=C)` bond with `(NH_(2))` group .
For example,
1. `underset(1-"Amino prop-1-yne")(H_(3)overset(3)(C )-overset(2)(C )-=overset(1)(C )-NH_(2))`
2. `underset(1-"Amino prop-2-yne")(Hoverset(3)(C )-overset(2)(C )-=overset(1)(CH_(2))-NH_(2))`
`iii` It may contain two `(C=C)` bonds with `(NH_(2))` group or `(= NH)(` imine group).
For example,
1. `underset(1-"Amino prop-1,2-diene")(H_(2)overset(3)(C )=overset(2)(C )=overset(1)(CH)-NH_(2))`
2.
3 `underset("Prop-2-enalimine")(Hoverset(3)(C_(2))=Coverset(2)(H)-overset(1)(CH)=NH)`
`iv` It may contain one ring one `(C=C)` bond with `(NH_(2))` or `(=NH)` group.
For example.
`1.`

`1-` Amino cycloprop `-1-` ene

`1-` Amino cycloprop `-2-` ene

Cyclopropanlimine
Ten isomerica structures are possible.
`d.` `CH_(4)O_(3)Simplies` Discard `O` and `S` and `-4H` for each` S` atom `implies CH_(4-4)=C`
`D.U. =((2xx1+2)-0)/(2)=2^(@)`
It cannot have `(C=C)` or `(C-=C)` bond or ring because there is only one `C` atom. So, `S` atom with two `(S=O)` groups is possible.
Therefore, only one structure is possible.
`[CH_(3)-overset(O)overset(||)underset(O)underset(||)(S)-OH]D.U.=2`
Methyl sulphonic acid