how much should the present be increased in order to decrease the volume of a gas by 5% at constant
Your question is complete. You didn't provided which percentage you want the Temperature or the pressure. Now the general equation is P1V1/T1=P2V2/T2. Now for constant Pressure, p1=p2 and for constant T, T1=T2. Put the necessary values and you will get the results.
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