Answer
The structural isomers of $C_{5}H_{10}$ excluding any cyclic isomers (see figure)
Work Step by Step
From the molecular formula, it is clear that this is an alkene (general formula of alkene: $C_{n}H_{2n}$)
(i) Now, draw 5 C in a straight chain. Add a double bond in between C1 and C2 position. Remaining valency of C atoms are filled with H. we get one structural isomer i.e. 1-pentene.
(ii) Draw 5 C in a straight chain. Add a double bond in between C2 and C3 position. Remaining valency of C atoms are filled with H. we get another structural isomer i.e. 2-pentene.
(iii) Draw 4 C in a straight chain. Add a double bond in between C1 and C2 position. Place a methyl substituent group at C2 position. We get another structural isomer i.e. 2-methyl-1-butene.
(iv)Draw 4 C in a straight chain. Add a double bond in between C1 and C2 position. Place a methyl substituent group at C3 position. We get another structural isomer i.e. 3-methyl-1-butene.
(v)Draw 4 C in a straight chain. Add a double bond in between C2 and C3 position. Place a methyl substituent group at C2 position. We get another structural isomer i.e. 2-methyl-2-butene.
