Which of the following is the correct order of boiling points for $(1^o)$ primary,$(2^o)$ secondary,and $(3^o)$ tertiary alcohols?

Which among the following compounds reacts fastest with $HBr$?

Ethylene glycol,on oxidation with periodic acid $(HIO_4)$,gives:

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

Rate of dehydration of alcohols follows the order

Which one of the following compounds will provide a tertiary alcohol on reaction with excess of $CH_3MgBr$ followed by hydrolysis?