Formation of diethyl ether from ethanol is based on a

The compound which gives the most stable carbonium ion on dehydration is

The major product of the following reaction is: $CH_3CH(OH)CH_3 \xrightarrow{Cu, 573 \ K} ?$

The high boiling point of ethanol $({78.2 \ ^\circ C})$ compared to dimethyl ether $({-23.6 \ ^\circ C})$,though both have the same molecular formula $C_2H_6O$,is due to

The reaction shown in the image proceeds by the $.......$ mechanism.
$CH_3CH_2CH(OH)CH_3 + SOCl_2 \rightarrow CH_3CH_2CH(Cl)CH_3 + SO_2 + HCl$

In chromic acid oxidation of alcohol,the chromium is