When hydrogen gas burns in the presence of oxygen, atoms are rearranged and a new substance is formed. Because a new substance is formed, which of these statements must BEST describe what happens?

Question

a. The properties of the new substance are different, so a physical change took place.
b. The properties of the new substance are the same, so a physical change took place.
c. The properties of the new substance are different, so a chemical change took place.
d. The properties of the new substance are the same, so a chemical change took place.

Answer 1

The correct answer is:

c. The properties of the new substance are different, so a chemical change took place.

When hydrogen gas burns in the presence of oxygen, it undergoes a chemical change resulting in the formation of water (H₂O), which has different properties compared to the original substances (hydrogen and oxygen gases).