Answer
See the detailed answer below.
Work Step by Step
a) Since the mass is slowly removed, the pressure decreases slowly. This means that the volume increases slowly either. And since the volume increases the temperature decreases.
Also, since there is no heat exchange because the cylinder is fully isolated, this means that it is an adiabatic process.
Thus,
$$\boxed{Q=0}$$
The gas expands which means that the final volume is greater than the initial volume. Hence, the work is negative.
$$\boxed{W\lt 0}$$
And since the gas expands,
$$\boxed{\Delta T\lt 0}$$
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See the graph below.
