In the structure given below, how many heteroatoms are present?

Hint:
Heteroatoms are defined as the atoms other than carbon and hydrogen in a given compound. There are limited number of hetero atom in a compound. In a compound there cannot be more than three heteroatoms.

Complete answer:
-Heteroatoms are non hydrogen or non carbon atoms that have replaced carbon or hydrogen in the molecular structure.
-These atoms will have lesser or greater attraction for the electrons than the carbon atom.
-The bond that is present between carbon and the heteroatom is polar in nature.
-Heteroatoms affect the reactivity of the organic molecule.
-The examples of heteroatoms are: oxygen, nitrogen, bromine, chlorine, sulphur, phosphorus, iodine, lithium and magnesium.
-In the diagram given below:

There is only one heteroatom present in a compound and that is oxygen.
Therefore, the compound given in the diagram consists of only one heteroatom.

Additional information:
Example of a compound which consists of two heteroatoms and that is acetamide.
The structure of acetamide is given below as follows:

In the given structure there are two heteroatoms present namely: oxygen and nitrogen.
Likewise , we can identify heteroatoms on the basis of the molecular formula also.

Note:The polarity between carbon and oxygen bonds depends on the electron attracting properties of these atoms. For example if there are 2 oxygen atoms in a compound, it will still be considered as one heteroatom because we are only supposed to know which atom is there and not the number of the same heteroatom in a compound.