Question

1 mole of a hydrocarbon ‘X’ undergoes complete saturation with 1 mole of hydrogen in presence of a heated catalyst. What would be the formula of ‘X’?

• A. $C_2{H}_6$
• B. $C_2{H}_2$
• C. $C_5{H}_{10}$
• D. $C_7{H}_{16}$

Answer 1

The correct option is C

${\mathrm{C}}_5{\mathrm{H}}_{10}$

Saturated Hydrocarbon: The hydrocarbon contains only a single bond between atoms. The general formula of saturated hydrocarbon is ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}+2}$.

The organic compounds containing carbon atoms having multiple bonds either double bonds or triple bonds between two carbon atoms are called unsaturated hydrocarbons.

(i) Alkenes and alkynes are unsaturated hydrocarbons that contain double bonds and triple bonds between the C and H atoms.

(ii) The general formula of alkene is ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}}$ and for alkyne is ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}-2}$.

(iii) Ethene and ethyne are called unsaturated hydrocarbons.

1 mole of unsaturated hydrocarbon is converted to saturated hydrocarbon in the presence of 1 mole of hydrogen gas (${\mathrm{H}}_2$) with the heated catalyst.

${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}}\stackrel{{\mathrm{H}}_2}{\to }{\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}+2}$

(c) X is the unsaturated hydrocarbon and ${\mathrm{C}}_5{\mathrm{H}}_{10}$ satisfies the general formula of unsaturated hydrocarbon.

(a) ${\mathrm{C}}_2{\mathrm{H}}_6$ the compound does not satisfy ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}}$ this formula since there are 2 Carbon atoms and there must be 4 Hydrogen atoms to satisfy the formula.

(b) ${\mathrm{C}}_2{\mathrm{H}}_2$ the compound does not satisfy ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}}$ this formula since there are 2 Carbon atoms and there must be 4 Hydrogen atoms to satisfy the formula..

(d) ${\mathrm{C}}_7{\mathrm{H}}_{16}$ the compound does not satisfy ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}}$ this formula since there are 7 Carbon atoms and there must be 14 Hydrogen atoms to satisfy the formula..

Option C is the correct answer.