A carbon compound ‘P’ on heating with excess conc. H,So, forms another carbon compound ‘Q’ which on addition of hydrogen in the presenc

A carbon compound ‘P’ on heating with excess conc. H,So, forms another
carbon compound ‘Q’ which on addition of hydrogen in the presence of nickel
catalyst forms a saturated carbon compound ‘R’. One molecule of ‘R’ on
combustion forms two molecules of carbon dioxide and three molecules of water.
Identify P, Q and R and write chemical equations for the reactions involved.​