a) A combound which contains only Carbon and Hydrogen. There are covalent bonds between atoms. Hydrogen form one single bond and Carbon forms four covalent bonds. Carbon bonds can be single, double or triple bonds.
All hydrocarbons are organic compounds, but organic compound can include atoms of other elements.
b) Alkyne has a covalent triple bond between two carbon atoms. Simplest alkyne is ethyne HCCH.
b) Alkane contains only Carbon and Hydrogen and there are single bonds
between atoms. Simplest alkane is methane CH4.
c) An alkene has one double bond between Carbon atoms. Simplest
alkene is ethene H2C=CH2.