Concept:Alkenes react with concentrated sulphuric acid to form alkyl hydrogen sulphate, which can be hydrolysed to alkanols.
Explanation:An alkene, e.g. propene, reacts with concentrated tetraoxosulphate(VI) acid,
H2SO4.
This initial addition forms an alkyl hydrogen tetraoxosulphate(VI), such as
CH3CH(OSO3H)CH3.
When this product is boiled with water, it undergoes hydrolysis.
The hydrolysis produces the corresponding alkanol and regenerates the acid.
Thus, the first key reagent needed is concentrated tetraoxosulphate(VI) acid.
Options involving bromine, aqueous permanganate, or sodium hydroxide do not give this industrial route to alkanols.
Answer:B. concentrated tetraoxosulphate(VI) acid.