On passing vapours of an organic liquid over finely divided $Cu$ at $573 \, K$,the product was an alkene. This reaction is:

The order of reactivity of the following alcohols with halogen acids is . . . . . .
$(A)$ $CH_3-CH_2-CH_2-OH$
$(B)$ $CH_3-CH_2-CH(OH)-CH_3$
$(C)$ $CH_3-CH_2-C(CH_3)_2-OH$

Ethyl alcohol gives ethyl chloride with the help of ..........

The reaction of ethylene glycol with $PI_3$ gives:

$A$ hydroxy compound $(X)$ with molar mass $122 \ g \ mol^{-1}$ is acetylated with acetic anhydride,using a large excess of the reagent ensuring complete acetylation of all hydroxyl groups. The product obtained has a molar mass of $290 \ g \ mol^{-1}$. The number of hydroxyl groups present in compound $(X)$ is :

What is obtained when ethyl alcohol is heated with red phosphorus and $HI$?