Pure acetic acid is known as glacial acetic acid because:

Given three acids:

The correct order of ease of acid catalysed esterification is:

${\mathrm{C}}^{*}$ is within the product:

The product, of which of the following reaction is capable of changing orange colour of ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$ to green colour of ${\mathrm{Cr}}^{+3}$?

Which of the following reagents can be used in step-1?