Dna is different from rna in that
a. rna is made up five bases, whereas dna is made up of four.
b. in general, rna molecules are longer than dna molecules.
c. rna contains an additional oxygen atom on the ribose sugar.
d. rna cannot exist as a double helix. all of these statements are true.

RNA contains an additional oxygen atom on the ribose sugar. (Ans. C)

Explanation:

RNA contains a sugar which is known as ribose, and which contains an extra group of hydroxyl (OH-) while DNA contains deoxyribose sugar.

RNA contains four nitrogenous bases cytosine, adenine, guanine, and uracil, while DNA contains cytosine, adenine, guanine, and thymine.

Double helix means two stranded structure like DNA, while RNA is single stranded.

DNA molecule is much longer polymer than RNA molecule.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.