Matching rate measurement methods to reaction products Steps:

• Reaction 1 produces AgCl precipitate, which clouds the solution and obscures a cross underneath the container.
• Reaction 2 produces CO2 gas, causing measurable mass loss as the gas escapes.
• Disappearing cross method tracks time for visibility loss due to precipitate in Reaction 1.
• Loss of mass method tracks mass decrease over time due to gas in Reaction 2.

Why D is correct:

• D pairs disappearing cross with Reaction 1's precipitate (obscures view per method definition) and loss of mass with Reaction 2's gas (mass change from escaping CO2).

Why the others are wrong:

• A: Disappearing cross fails for Reaction 2—no precipitate, so cross stays visible.
• B: Loss of mass fails for Reaction 1—no gas, so no mass change.
• C: Loss of mass fails for Reaction 1 (no gas); disappearing cross fails for Reaction 2 (no clouding).

Final answer: D