A different mixture is formed in each case. A different solution is formed in each case. Both a change of state and of elements is involved. New molecules are formed but the same elements exist.
Oxygen reacts with iron to produce rust and with hydrogen to produce water. Which statement describes both reactions?

Options:
- A different mixture is formed in each case.
- A different solution is formed in each case.
- Both a change of state and of elements is involved.
- New molecules are formed but the same elements exist.

New molecules are formed but the same elements exist.