Chemistry · Thermochemistry

In thermochemistry, the sign convention for work is that when work is done on the system, it is considered positive. This is because the system gains energy in the form of work. Option C is correct as it aligns with this convention. Option A is incorrect because it suggests a negative work, which would mean energy is leaving the system. Option B is incorrect because, while boundary conditions affect the amount of work, the question is about the convention, not the conditions. Option D is incorrect because it describes a scenario where no work is done, which is not applicable here.

In chemistry, work done on the system is considered positive because it adds energy to the system. Therefore, this option is incorrect.

While boundary conditions can affect the magnitude of work, the sign convention in chemistry remains that work done on the system is positive, making this option incorrect.

In thermochemistry, work done on the system is positive because it increases the energy of the system. This reflects the standard convention used in chemistry, making this option correct.

Work done can be zero if no energy is transferred as work, but the question specifies 'work done on the system,' which means energy is added, not zero. Thus, this option is incorrect.