Question

Compounds are substances in which two or more atoms are chemically combined to form a new,

pure substance. Which of the following substances is NOT a compound
If you can please help with both if you can

Answer 1

`H_2` (hydrogen) is not a compound because it's not made of more than one element. Yes we have more than one component, but both components are of the same element H.

Something like
`CO_2` is a compound because it's made of carbon and oxygen (specifically 1 carbon and 2 oxygen), so we have at least two different elements here.