What condition must be true when conducting temperature volume measurement?

Why would a rubber balloon be a poor system for this kind of expirement?

The general equation is
(P1V1)/T1 = (P2V2)/T2
If V and T are being studied, then P must be held constant. Would you think P could be held constant in a rubber balloon?

hallo temperatureis a measurement of how hot things are the relation ship is that they are both in a water

At 25 degrees C a balloon takes up a 2L volume what will the new volume be