To evaluate the statements, let's analyze them one by one:
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Statement 1: "For the work done on the system we can write \( w = pdV \)"
- This statement is generally true in the context of thermodynamics. Work done on a system during a quasi-static process can be expressed as \( w = \int p , dV \), where \( p \) is the pressure and \( dV \) is the change in volume. For infinitesimal processes, this can be simplified as \( w = pdV \) when pressure is constant.
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Statement 2: "We can only use \( c \) and \( c \) for a process in which the pressure or the volume, respectively, stays constant."
- The statement appears to have a typographical error with "c and c." If it refers to specific heat capacities, then it is true that \( c_p \) (specific heat at constant pressure) and \( c_v \) (specific heat at constant volume) are defined for processes where pressure or volume, respectively, is constant.
Based on this analysis:
- Statement 1 is true.
- Statement 2 is also true (assuming it refers to specific heat capacities).
Thus, the answer is:
Both statement 1 and statement 2 are true.