human
Question: Oxygen reacts with iron to produce rust and with hydrogen to produce water. Which statement describes both reactions?

Choices:
A) A different mixture is formed in each case.
B) A different solution is formed in each case.
C) Both a change of state and of elements is involved.
D) New molecules are formed but the same elements exist.
gpt
The correct answer is 3: New molecules are formed but the same elements exist..