1. 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
Answer: C
The new mass will be the same as the original mass.
When the candle burns, it converts wax into gases through combustion, but the total mass of the system remains unchanged when measured in a closed container like the jar. Therefore, the mass recorded after the candle extinguishes will equal the original mass.
A) will be less than the original mass
This option is incorrect because while the candle burns, it releases gases, but the mass of the remaining wax and gases in a closed system will still equal the original mass due to the law of conservation of mass.
B) will be greater than the original mass
This choice is incorrect as well because the mass cannot increase in a closed system. The gases produced during combustion do not add mass; they simply transform the wax into different states, maintaining the original mass.
C) will be the same as the original mass
This option is correct. The principle of conservation of mass states that in a closed system, mass is neither created nor destroyed. Thus, despite the burning of the candle, the combined mass of the jar, remaining wax, and combustion gases will equal the original mass.
D) cannot be determined accurately because there is no longer a flame on the candle
This option is incorrect. While the flame is extinguished, the mass can still be accurately determined. The absence of the flame does not affect the total mass of the closed system.
Conclusion
The correct answer is that the new mass will be the same as the original mass because the law of conservation of mass applies in this scenario. Options A and B suggest changes in mass that contradict this fundamental principle, while option D incorrectly implies uncertainty in measurement despite the system being closed.