The number of possible alcoholic isomers for $C_4H_{10}O$ are

Which of the following responds to a positive $(+ve)$ iodoform test?

Arrange the following alcohols in increasing order of reactivity towards elimination reaction:
$(I)$ $NO_2-CH_2-CH_2-CH_2-CH_2OH$
$(II)$ $CH_3-CH_2-CH(NO_2)-CH_2OH$
$(III)$ $CH_3-CH(NO_2)-CH_2-CH_2OH$
$(IV)$ $CH_3-CH_2-CH_2-CH_2OH$
Select the answer from the codes given below:

An alcohol $X$ $(C_5H_{12}O)$ on dehydration gives $Y$ (major product). Reaction of $Y$ with $HBr$ gave $Z$ ($C_5H_{11}Br$,major product). $Z$ undergoes nucleophilic substitution in two steps. What are $X$ and $Y$?

Which of the following compounds does $NOT$ respond positively to the iodoform test?

Which of the following compounds will form a hydrocarbon on reaction with Grignard reagent?