Answer:
For each scenario as following:
A. 3 Potential deaths by chlorine exposure
B. 1 Potential deaths by chlorine exposure
C. 3 Potential deaths by chlorine exposure
Explanation:
According to Freitag, 1941 Chlorine exposure can be lethal at the concentration of 34-51 ppm in a time of 1h-1.5h. The answers are based on his reference.
This problem is providing the mass, energy, initial temperature and specific heat of a sample of copper that is required to calculate the final temperature.
Thus, we recall the general heat equation:

Which has to be solved for the final temperature,
as follows:

Finally, we plug in the numbers to obtain:

However, this result is not given in the choices.
Learn more:
Protons and neutrons.
Note: They probably are ABOUT the same mass. Don't think they are exactly the same.
Hope this helps!