Question

what do these two changes have in common?
sauce burning on a stove
a piece of pizza rotting in a trashcan
select all that apply.
both are only physical changes. both are chemical changes.
both are caused by heating. both are caused by cooling.

Explanation:

1. Analyze "sauce burning on a stove": Burning involves a chemical reaction (combustion) where the sauce's components react with oxygen, forming new substances (like ash, smoke, different compounds). It's a chemical change, and heat (from the stove) causes it.
2. Analyze "a piece of pizza rotting in a trashcan": Rotting is a decomposition process by microorganisms (like bacteria, fungi), which is a chemical change (new substances like mold, gases are formed). Heat in the environment (trashcan can be warm) can accelerate rotting, but the key commonality in terms of change type is chemical.
3. Evaluate options:

• "Both are only physical changes": Incorrect. Physical changes don't form new substances; burning and rotting do (chemical changes).
• "Both are chemical changes": Correct. Both burning (combustion) and rotting (decomposition) involve chemical reactions with new substances formed.
• "Both are caused by heating": Partially true for burning (stove heat), but rotting is caused by microbial action (heat can speed it, but not the direct cause like burning). However, among the options, this is more plausible than the others. Wait, no—actually, rotting is mainly due to microbes, not direct heating. Wait, maybe the initial analysis was wrong. Wait, let's re - check. Burning: chemical change, caused by heat. Rotting: chemical change (decomposition), and heat can facilitate microbial growth (so heat is a factor). But the main common change type is chemical. Wait, the options: the correct one should be "Both are chemical changes". Let's re - evaluate each option:
• "Both are only physical changes": Wrong, as both are chemical.
• "Both are chemical changes": Correct, as burning (combustion, new substances) and rotting (decomposition, new substances) are chemical changes.
• "Both are caused by heating": Burning is caused by heat (stove), but rotting is caused by microbes (though heat can accelerate). So this is not a universal common cause.
• "Both are caused by cooling": Wrong, both involve processes that are not caused by cooling.

So the correct option is "Both are chemical changes".

Answer:

Both are chemical changes.