Which of the following is the example of a compound?

A compound is made up of two or more elements in a predetermined mass proportion. It is a pure substance that cannot be physically divided into constituents. 

When two or more atoms make chemical bonds with each other, a compound is formed. 

Water is a compound because physical means cannot separate it into its constituent elements. 

The properties of water differ significantly from those of its main constituents hydrogen and oxygen. 

Water has the chemical formula ${\mathrm{H}}_2\mathrm{O}$ which indicates that each molecule has one oxygen atom chemically linked to two hydrogen atoms.