Answer : The correct option is, octane [tex](C_8H_{18})[/tex]
Explanation :
Covalent compound : It is a compounds in which atoms are covalently bonded. It is formed by the equal sharing of electrons. These bonds are commonly formed between two non-metals.
Ionic compound : It is a compounds in which atoms are bonded through ionic bond. It is formed by the complete transfer of electrons. The atom that looses the electron is considered as electropositive atom and the atom that gains the electron is known as electronegative atom. These bonds are formed between one metal and one non-metal.
Organic compound : It is a hydrocarbon that contains hydrogen and carbon and the hydrogen and the carbon are covalently bonded to each other. There are two types of hydrocarbon which are saturated hydrocarbon and unsaturated hydrocarbon.
Saturated hydrocarbon : These are the compounds which containing single bonds between the carbon-carbon atoms. In saturated compounds, there are more number of hydrogen bonded with the carbon atom.
Unsaturated hydrocarbon : These are the compounds which containing double and triple bonds between the carbon-carbon atoms. In unsaturated compounds, there are less number of hydrogen bonded with the carbon atom.
From the given options, we conclude that
Ammonia [tex](NH_3)[/tex], is the covalent compound in which two non-metals (nitrogen and hydrogen) are covalently bonded.
Calcium sulfide [tex](CaS)[/tex], is the ionic compound in which calcium (metal) and sulfur (non-metal) are bonded through ionic bond.
Sulfur trioxide [tex](SO_3)[/tex], is the covalent compound in which two non-metals (sulfur and oxygen) are covalently bonded.
Octane [tex](C_8H_{18})[/tex], is an organic compound in which hydrogen and carbon atoms are present. It is a saturated hydrocarbon.
Hence, the correct option is, octane [tex](C_8H_{18})[/tex]
