Thermal 2 tutorial is about heat loss equal to heat gain. The commone errors are taking the lower temp and deduct a higher temp is not allowed as it is about equating 2 magnitudes of heat energy.
Question 4 is part thermal 2 and thermal 3. It is the most common process of boiling water . At boiling point , The water absorbs heat but the temperature is not changing but the steam is forming. Translate into first law of thermodynamics change in U =0 , hence is Q is positive , W must be negative. This is exactly absorbing heat and work is done by the gas.
