Question

what do these two changes have in common?
rain forming in a cloud
cellular respiration
select all that apply.
both are changes of state.
both are caused by heating.
both are chemical changes.
both conserve mass.

Explanation:

• Rain forming in a cloud: This is a physical change (change of state, from gas to liquid). Mass is conserved in physical changes. It occurs due to cooling (condensation), not heating.
• Cellular respiration: This is a chemical change (glucose + oxygen → carbon dioxide + water + energy). Mass is conserved in chemical reactions (Law of Conservation of Mass). It involves energy release, not direct heating as a cause.
• Analyzing options:
• "Both are changes of state": Incorrect, as cellular respiration is a chemical change, not a state change.
• "Both are caused by heating": Incorrect, rain forms from cooling (condensation), and cellular respiration is not caused by heating.
• "Both are chemical changes": Incorrect, rain formation is a physical change.
• "Both conserve mass": Correct, as both physical (rain formation) and chemical (cellular respiration) changes follow the Law of Conservation of Mass.

Answer:

D. Both conserve mass.