An alkene $'A'$ contains three $C-C$,eight $C-H$ $\sigma$ bonds and one $C-C$ $\pi$ bond. $'A'$ on ozonolysis gives two moles of an aldehyde of molar mass $44 \ u$. Write the $IUPAC$ name of $'A'$.

(A) As per the given information,$'A'$ on ozonolysis gives two moles of an aldehyde of molar mass $44 \ u$. The formation of two moles of an aldehyde indicates the presence of identical structural units on both sides of the double bond. The molar mass of the aldehyde is $44 \ u$,which corresponds to ethanal $(CH_3CHO)$.
Since two moles of ethanal are produced,the alkene must be $CH_3-CH=CH-CH_3$ (but-$2$-ene).
Verification of bonds in but-$2$-ene $(C_4H_8)$:
- $C-C$ $\sigma$ bonds: $3$ $(C_1-C_2, C_2-C_3, C_3-C_4)$
- $C-H$ $\sigma$ bonds: $8$
- $C-C$ $\pi$ bond: $1$
Ozonolysis reaction:
$CH_3-CH=CH-CH_3 + O_3 \to \text{ozonide} \xrightarrow{Zn/H_2O} 2CH_3CHO$
The $IUPAC$ name of $'A'$ is but-$2$-ene.