Question

what do these two changes have in common?
water freezing into ice
snowflakes forming in a cloud
select all that apply.
both are only physical changes. both are chemical changes.
both are caused by heating. both are caused by cooling.

Explanation:

• Physical change: In water freezing into ice and snowflakes forming in a cloud, the chemical composition of water (\(H_2O\)) remains the same. Freezing is a phase change from liquid to solid, and snowflake formation involves water vapor (gas) turning into solid (ice crystals) through processes like deposition. There is no new substance formed, so these are physical changes.
• Caused by cooling: Water freezes when it loses heat (cools down). Snowflakes form when water - vapor in the cloud cools. The cooling causes the water molecules to slow down and arrange themselves in an ordered (solid) state for ice (in the case of freezing water) and for ice crystals (in the case of snowflakes).

Answer:

• A. Both are only physical changes.
• D. Both are caused by cooling.