why is it possible for the temperature of a system to remain constant even though heat is released or absorbed by the system?

Isothermal Process

Explanation:

In this process heat is released or absorbed by the system happens at very slow rate in order to continually maintain the temperature of the system through heat exchange. so ΔT = 0 ⇒ ΔU = 0

First law of Thermodynamics ΔQ = ΔU + ΔW

⇒ ΔQ = ΔW

e. g Carnot Cycle