Praxis 5511 Practice Test Practice Question
A lit candle is attached to a jar lid, and the lid is then screwed tightly onto the jar as shown in Figure A. The mass of the jar with the candle burning inside it is determined. When the flame extinguishes, the candle and jar appear as in Figure B. When the jar and candle as shown in Figure B are weighed, the new mass
Correct Answer: C
Rationale: When the candle burns inside the sealed jar, it consumes wax and oxygen, producing carbon dioxide and water vapor. However, these gases remain trapped within the jar, resulting in no loss of mass. Therefore, when the candle extinguishes, the total mass of the jar, candle remnants, and combustion products remains unchanged.
Option A is incorrect; the mass does not decrease, as all materials are contained. Option B is also wrong; the mass cannot increase since no additional material is introduced. Option D misinterprets the situation; the absence of a flame does not affect the overall mass, as all components remain inside the jar.
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