Which among the following is a Lucas reagent?

Which of the following compounds yields propanone upon dehydrogenation?

Identify $A, B, C,$ and $D$ in the following reaction sequence:
$CH_3-CH_2-CH(OH)-CH_3$ $\xrightarrow{PBr_3} (A)$ $\xrightarrow{Mg, \text{ether}} (B)$ $\xrightarrow{CH_3CHO} (C)$ $\xrightarrow{H_3O^+} (D)$

What is the decreasing order of reactivity of $HX$ in the reaction $ROH + HX \to RX + H_2O$?

Which of the following compounds cannot be synthesized by the reaction of a Grignard reagent?

What is the product obtained when the reaction of $CH_2-CH_2$ (epoxide) with $RMgX$ is followed by hydrolysis?