Total number of isomers (including stereoisomers) obtained on monochlorination of methylcyclohexane is $........$

"$P$" is a hydrocarbon with the molecular formula $C_8H_{14}$. On ozonolysis,"$P$" forms "$Q$". "$Q$" on treatment with alkali under reflux conditions produces "$R$",which on treatment with $I_2/NaOH$ gives a yellow precipitate. Acidification of the solution gives "$S$". The structure of "$S$" is given below:
(Structure $S$: $1-$methyl$-2-$oxocyclopentanecarboxylic acid derivative or similar cyclic structure as per common reaction pathways).
The correct structure of "$P$" is:

Provide the classification of hydrocarbons.

What is the correct order of acidity for the following hydrocarbons?

What is the number of bonds in allyl isocyanide?

In laboratory burners,we use