Question

what is the molecular formula of marsh gas

Answer 1

1)  Compound Name  = marsh gas
2)  Molecular Formula  =   CH4
3)  Molecular Weight   = 16.04246
 

Answer 2

molecular formula of marsh gas is $CH_4$. after all marsh has is another name of methane gas.

yes, methane gas is also known as $\textbf{marsh gas}$ or $\textbf{natural gas}$. and you should know methane is the simplest compound of saturated hydrocarbon. it is first compound of alkane group.

well you know, there are mainly three types of hydrocarbons.

(1) alkane : it is known as saturated hydrocarbon because there exists only single covalent bonds between adjacent carbon atoms. example of alkane are ; methane (CH4), ethane (C2H6), propane (C3H8) etc..

(2) alkene : it is known as unsaturated hydrocarbon because there exists double covalent bonds between adjacent carbon atoms.

example ; ethene (C2H4) etc.

(3) alkyne : it is also known as unsaturated hydrocarbon because there exists triple covalent bonds between adjacent carbon atoms. example ; ethyne(C2H2) etc..