Enzymes in a reaction act as catalysts. They speed up the chemical reaction process.
Answer:
Option C. The number of oxygen atoms is the same before and after the reaction.
Explanation:
When hydrogen combine with oxygen, water is formed. According to law of conservation of matter, matter cannot be created nor destroyed during a chemical reaction. So according to this law, the amount of reactants is equal to the amount of product produced after a chemical reaction and the number of oxygen atoms is the same before and after the reaction.
Umbilical cord. The umbilical cord attaches the fetus to the placenta. The cord contains blood vessels that bring nutrients to the developing fetus.
