Methyl alcohol on oxidation with acidified $K_2Cr_2O_7$ gives

The compound which will give a negative iodoform test is

The substitution of the $-OH$ group of an alcohol or the $-COOH$ group of a carboxylic acid with a $-Cl$ atom is achieved by using which of the following?

The reaction of ethylene glycol with $PI_3$ gives:

Which of the following compounds will give the most stable carbonium ion during dehydration?

$CH_3-CH_2-CH=CH_2$ $\xrightarrow[CCl_4]{HCl} X$ $\xrightarrow{Aq. NaOH} Y$ $\xrightarrow[\Delta]{Conc. H_3PO_4} Z$
The major product $Z$ is: