The correct option is D Sabatier-senderens reaction
Wurtz reaction: It is a coupling reaction thus, two alkyl halide will combine to form higher alkane. Hence, the smallest alkane that can be formed is ethane.
RX+2Na+XR→R−R+2NaX
Kolbe's electrolysis: Here, the salt of carboxylic acid will undergo decarboxylation to give alkanes.
CH4 can't be prepared by this method. The smallest alkane that can be formed is ethane (C2H6)
2RCOOK+2H2Oelectrolysis⟶R−R+2CO2+2KOH+H2
Sabatier senderens reaction: Here, unsaturated hydrocarbon is reduced to alkane. The minimum carbon chain of unsaturated hydrocarbon is two i.e., Ethene. Hence, it reduced to form Ethane.
CnH2n+H2Ni→CnH2n+2
Soda Lime reaction: Here, carboxylic acid will undergo decarboxylation to form alkane containing one C atom less than the carboxylic acid.
Thus, acetic acid will form methane by Soda Lime reaction.
CH3COOHNaOH⟶CH3COONa+H2O
CH3COONa+NaOHCaO−−→ΔCH4+Na2CO3.