The major product obtained when ethanol is heated with excess of conc. $H_2SO_4$ at $443 \ K$ is:

What is the final product $(IV)$ in the following reaction sequence? $CH_3-CH(OH)-CH_3$ $\xrightarrow{PBr_3} I$ $\xrightarrow{Mg/ether} II$ $\xrightarrow{\text{Ethylene oxide}} III$ $\xrightarrow{H_2O} IV$

When benzyl alcohol is oxidised with $KMnO_4$,the product obtained is

The substitution of the $-OH$ group of an alcohol or the $-COOH$ group of a carboxylic acid with a $-Cl$ atom is achieved by using which of the following?

Which combination of alkyl bromide and epoxide can be used to prepare the following product by addition of the Grignard reagent derived from the alkyl bromide to the epoxide?

$A$ compound with formula $C_4H_{10}O$ on oxidation gives $C_4H_8O$,which forms an oxime and gives a positive iodoform test. The original compound on reaction with concentrated $H_2SO_4$ gives $C_4H_8$. What is the structure of the compound?