Question

If a carbon hydrate has 10 carbon what other elements would be present?

10 Hydrogen, 20 nitrogen

10 oxygen, 20 nitrogen

10 oxygen, 20 hydrogen

10 hydrogen 10 nitrogen

Answer 1

10 oxygen, 20 hydrogen

Step-by-step explanation:

A hydrate is a compound that contains the elements of water in a ratio of 2H:1O.

The only option that fits is 10 oxygen, 20 hydrogen.

The other options are wrong, because the hydrate portion of a molecule does not contain nitrogen.

Answer 2

In addition to the 10 carbon atoms, a molecule of this carbohydrate could also contain 10 oxygen, and 20 hydrogen atoms.

Step-by-step explanation:

Think about the word "carbohydrates." The prefix "carbo-" indicates that there are carbon atoms in this compound. On the other hand, the "-hydrate" part of the name hints that this compound also contains hydrogen and oxygen (the two elements that form water.) That's exactly the case- carbohydrates contain exactly three elements: carbon, hydrogen, and oxygen. That rules out the second and the fourth choice: the molecule can't be a carbohydrate if it contains nitrogen atoms.

In particular, for this molecule to be a carbohydrate, the ratio between the number of H and O atoms in it should be the same as that in water. In a water molecule, there are twice as many H atoms as O atoms. So is the case in a carbohydrate molecule.

Among all four choices, only the third one meets both requirements. The molecular formula of this carbohydrate would be
`\rm C_(10) H_(20) O_(10)`, which is equivalent to
`\rm C_(10)(H_(2)O)_(10)`. Hence the name "carbohydrate."