Question

what do these two changes have in common?
cooking a pancake
burning a candle
select all that apply.
both are only physical changes.
both are chemical changes.
both are caused by heating.
both are caused by cooling.
submit
work it out
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Explanation:

1. Analyze "cooking a pancake": Cooking involves a chemical reaction (like protein denaturation, starch gelatinization) and is caused by heating. It's a chemical change, not just physical.
2. Analyze "burning a candle": Burning (combustion) is a chemical reaction (wax reacting with oxygen) and is caused by heating (ignition via heat). It's a chemical change.
3. Evaluate options:

• "Both are only physical changes": Incorrect, as both involve chemical changes.
• "Both are chemical changes": Correct, as both cooking and burning involve chemical reactions (new substances formed).
• "Both are caused by heating": Correct, as cooking uses heat (stove, pan) and burning a candle requires heat to ignite and sustain combustion.
• "Both are caused by cooling": Incorrect, as both processes require heat, not cooling.

Answer:

B. Both are chemical changes, C. Both are caused by heating