What do we mean when we say that the value of k2 depends upon the unit of volume? And also why doesnt k2 depend upon the unit of temperature?
This is given under Charles law , according to which at constant pressure, the volume of a fixed amount of a gas is directly proportional to its absolute temperature.
Now volume is directly proportional to the temperature so, if a quantity will depend on the volume it will automatically depends on the temperature also.
Dependence on the volume means that a quantity will change according to the volume.