Hardening of oil is done by

What is Baeyer's reagent?

How many moles of $BH_3$ are needed to react completely with $2 \ mol$ of $1$-pentene in a hydroboration-oxidation reaction?

$cis-3-hexene \xrightarrow{(a)} \text{meso } 3,4-hexanediol$
$trans-3-hexene \xrightarrow{(b)} \text{meso } 3,4-hexanediol$
Choose the pair of reagents $(a, b)$ for the above conversions.

How many alkenes on catalytic hydrogenation give isopentane as a product?

What do you mean by olefin? Give an example.