Question

a carbon compound P on heating with excess conc . H2 S o4 from another carbon compound Q which on addition of hydrogen or in the presence of nickel catalyst from a saturated carbon compound R. one molecule of R on combustion froms two molecules of carbon dioxide and three molecules of water. identify P,Q and R and write chemical equation for the reaction involved

Answer 1

As we know the last compound formed R on combustion gives 2 molecules of CO and three molecules of H2O. so the compound will contain 2 carbon atoms and 3 hydrogen atoms now, the compound R=C2H6 (ethane)
equation involved:-

R--------------->2CO2+3H2O

now will find other molecules by using the reaction given

finding Q
equation involved:-

Q+H2----------------->C2H6
so
Q=C2H4 (ethene)

finding P

conc.H2SO4 acts as a dehydrating agent
equation involved:-

P-------------------->C2H4+H2O
P=C2H5OH

hope it helps ...............
CHEERS:((