Complete combustion of 0.86 g of compound X gives 2.64 g of CO2 and 1.26 g of H2O. The lowest molecular mass X can have :

Moles of C=nCO2=2.6444=0.06⇒mass of C=0.72Moles of H = 2 x moles of H2O=2×1.2618=0.14mass of H = 0.14Compound does not contains oxygen,So, EF→C0.06H0.14⇒C3H7Lowest M,M. = 43