Question

what do these two changes have in common?
sauce burning on a stove
cellular respiration
select all that apply.
both are caused by cooling.
both are only physical changes.
both are chemical changes.
both conserve mass.

Explanation:

1. Analyze "sauce burning on a stove": Burning involves a chemical reaction (combustion) where new substances are formed, so it's a chemical change. According to the law of conservation of mass, mass is conserved in chemical reactions. Burning is caused by heating, not cooling.
2. Analyze "cellular respiration": Cellular respiration is a series of chemical reactions in cells to produce energy, forming new substances (like CO₂ and H₂O from glucose), so it's a chemical change. Mass is conserved in this biochemical process. It's not caused by cooling and is not a physical change.
3. Evaluate each option:

• "Both are caused by cooling": Incorrect, as both processes involve heating (burning needs heat, respiration is metabolic but not caused by cooling).
• "Both are only physical changes": Incorrect, both are chemical changes (new substances formed).
• "Both are chemical changes": Correct, as both involve chemical reactions with new substances.
• "Both conserve mass": Correct, as chemical reactions (including burning and cellular respiration) follow the law of conservation of mass.

Answer:

Both are chemical changes.
Both conserve mass.