What product is formed when ethyl alcohol is oxidized with $K_2Cr_2O_7$?

The major product obtained by the dehydration of the given alcohol is $:-$

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

When phenyl magnesium bromide reacts with $t-$butanol,the product would be

$(CH_3)_2CHOH$ $\xrightarrow{dil. \, [O]} X$ $\xrightarrow[(ii) \, H_2O]{(i) \, CH_3MgBr} Y$. What is $Y$ here?

The alcohol that produces turbidity immediately with $ZnCl_2 +$ conc. $HCl$ at room temperature is: