Question

what do these two changes have in common? using a large magnet to remove pieces of iron from a junkyard sewing an apron select all that apply. both are caused by cooling. both are changes of state. both conserve mass. both are caused by heating.

Explanation:

1. Analyze "using a large magnet to remove iron" and "sewing an apron":

• These are physical changes (no new substance formed). In any physical or chemical change, the law of conservation of mass holds (mass is neither created nor destroyed).
• "Caused by cooling/heating": Using a magnet doesn't involve temperature change, sewing an apron also doesn't relate to cooling/heating.
• "Changes of state": Removing iron with a magnet doesn't change state (solid iron remains solid), sewing an apron is about shaping fabric, not state change.

1. So only "Both conserve mass" is correct. The other options are incorrect.

Answer:

The correct option is: Both conserve mass. (The other options: "Both are caused by cooling", "Both are changes of state", "Both are caused by heating" are incorrect as using a magnet and sewing an apron don't involve cooling/heating or state changes, but mass is conserved in both physical processes.)