Praxis 5511 Practice Question
A student sets up an experiment as shown to test the law of conservation of mass. A mixture of copper and sulfur is heated to produce solid copper sulfide and gaseous sulfur dioxide, which is collected in a balloon. To ensure the data collected are valid, the student should
Correct Answer: A
Rationale: Using the same balance for determining the mass before and after heating ensures consistency and accuracy in measurements, which is vital for validating the law of conservation of mass.
Option B is misleading; measuring the mass before cooling is irrelevant if the balance is not consistent. Option C is incorrect because including the balloon's mass only after heating introduces variability and potential error. Option D is also wrong, as removing the balloon could lead to loss of gas, affecting the total mass measurement and compromising the experiment's integrity. Consistent measurement is key to valid results.
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