Cyclopentanol on reaction with NaH followed by CS₂ and CH₃I produces a/an

Oxidation of allyl alcohol with a peracid gives a compound of molecular formula C₃H₆O₂, which contains an asymmetric carbon atom. The structure of the compound is

The number of alkene (s) which can produce 2-butanol by the successive treatment of (i) B₂H₆ in tetrahydrofuran solvent and (ii) alkaline H₂O₂ solution is

Methoxybenzene on treatment with HI produces