Question

what do these two changes have in common? knitting yarn into a scarf ice melting in a cup 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 "knitting yarn into a scarf": This is a physical change as the yarn's shape is altered, no new substance is formed. It can be caused by human action (not directly heating/cooling in the sense of temperature change for the yarn's state, but ice melting is due to heating (absorbing heat to change from solid to liquid). Wait, correction: Knitting is a physical change (shape change), ice melting is a physical change (state change, solid to liquid, caused by heating as ice absorbs heat to melt).
2. Analyze "ice melting in a cup": Ice melting is a physical change (water changes state from solid to liquid, no new substance) and is caused by heating (the ice absorbs heat from the surroundings to melt).
3. Evaluate options:

• "Both are only physical changes": Correct, because knitting changes shape (physical) and ice melting changes state (physical), no new substances.
• "Both are chemical changes": Incorrect, no new substances in either, so not chemical.
• "Both are caused by heating": Ice melting is caused by heating (absorbing heat). Knitting is a manual process, but if we consider the environment, room temperature (which is warmer than ice, so ice melts by heating from surroundings; knitting is done at room temp, but the key is that ice melting is a physical change caused by heating, and both are physical. Wait, maybe the "heating" here is a bit loose, but the only correct physical change option is "Both are only physical changes". The other options: chemical is wrong, cooling is wrong (ice melts by heating, knitting isn't caused by cooling), and "caused by heating" – knitting isn't caused by heating (it's a mechanical process), so the only correct one is "Both are only physical changes". Wait, maybe I made a mistake earlier. Let's recheck:
• Physical change: change in form/state, no new substance. Knitting: shape change (physical). Ice melting: state change (physical). So both are physical changes.
• Chemical change: new substance, which neither has. So "Both are only physical changes" is correct. The other options: "caused by heating" – knitting is not caused by heating (it's a person knitting, not a temperature change causing the yarn to change shape). "caused by cooling" – ice melts by heating, not cooling. "chemical changes" – wrong. So the correct option is "Both are only physical changes".

Answer:

A. Both are only physical changes