Answer:
I think this is it.
Explanation:
As all the mass of other molecules are given and we have to find the mass of hydrogen so total subtracted by carbon and oxygen.
The type of substance that is most likely to contain a covalent bond is ONE THAT IS COMPOSED OF ONLY NON METALS.
Covalent bond is a type of chemical bond in which electron pairs are shared among the participating elements in order to achieve the octet form. Covalent bond is usually found among non metals.