Question

what do these two changes have in common? knitting yarn into a scarf your breath becoming visible on a cold day select all that apply. both are only physical changes. both are caused by heating. both are caused by cooling. both are changes of state.

Explanation:

Knitting yarn into a scarf is a physical change as it only changes the shape of the yarn, not its chemical composition. When your breath becomes visible on a cold day, it's because water vapor in your breath condenses into tiny liquid water droplets, which is also a physical change and a change of state (from gas - water vapor to liquid - water droplets). It is caused by cooling as the warm water - vapor in your breath cools down in the cold air. There is no heating involved in these two processes.

Answer:

Both are only physical changes.