What is the number of tertiary carbon atoms in a molecule of isobutane?

In the case of the homologous series of alkanes,which one of the following statements is incorrect?

$C_2H_6 \xrightarrow{450^{\circ}C} C_2H_4 + H_2$
The above reaction is called:

The reaction of an alkyl bromide $(X)$ with $Na$ in dry ether gives $4, 5-$diethyl octane. Then $(X)$ is:

Which type of hybridization is found in the $C-C$ single bond of an alkane and the $C=C$ double bond of an alkene?

Which of the following yields both alkane and alkene?