Compound '$A$' reacts with $PCl_5$ to give '$B$',which on treatment with $KCN$ followed by hydrolysis gives propanoic acid as the product. What is '$A$'?

Identify the reagents $X, Y, Z$ for the following dehydration reactions of alcohols:
$CH_3-CH_2-OH \xrightarrow{X} CH_2=CH_2 + H_2O$
$CH_3-CH(OH)-CH_3 \xrightarrow{Y} CH_3-CH=CH_2 + H_2O$
$(CH_3)_3C-OH \xrightarrow{Z} (CH_3)_2C=CH_2 + H_2O$

Identify the product of the following reaction: $\gamma$-butyrolactone + $BrMg-(CH_2)_4-MgBr$ $\xrightarrow[(ii) H_3O^{+}]{(i) THF}$

The compound $A$ on treatment with $Na$ gives $B$,and with $PCl_{5}$ gives $C$. $B$ and $C$ react together to give diethyl ether. $A, B$ and $C$ are in the order

Which of the following reactions takes place when tertiary butanol is passed over heated copper at $573 \ K$?

Which of the following alcohols cannot be prepared by the reaction of an acid chloride with an excess of a Grignard reagent followed by acidification?