What is the number of $\sigma$ bonds in $1$-butene?

$1-$Phenylbut$-1-$ene on ozonolysis gives

Identify products $[A]$,$[B]$,and $[C]$ in the following reaction sequence:
$CH_3-C \equiv CH$ $\xrightarrow{H_2, Pd/C} [A]$ $\xrightarrow[(ii) Zn, H_2O]{(i) O_3} [B] + [C]$

$\underset{C_7H_{14}}{(A)} \xrightarrow[Zn/AcOH]{O_3} (B) + (C)$
Compound $(A)$ exists as geometrical isomers and $(B)$ gives the Cannizzaro reaction. $(A)$ will be:

Ozonolysis of an organic compound gives formaldehyde as one of the products. This indicates the presence of:

On reaction with hot conc. $H_2SO_4$,which one of the following compounds loses a molecule of water?