X reacts with Na to evolve 1 mole of \[{{H}_{2}}\] gas, therefore the compound should have 2 active hydrogen atoms PER mole which is possible only in option d. \[C{{H}_{2}}OHC{{H}_{2}}C{{H}_{2}}OH+2Na\xrightarrow{{}}\] \[NaOC{{H}_{2}}C{{H}_{2}}C{{H}_{2}}C{{H}_{2}}ONa+2H\]