A cylinder containing an ideal gas is in a vertical position and has a piston of mass \(M\) that is able to move up or down without friction (figure). If the temperature is increased,
| 1. | both \(P\) and \(V\) of the gas will change. |
| 2. | only \(P\) will increase according to Charles' law. |
| 3. | \(V\) will change but not \(P.\) |
| 4. | \(P\) will change but not \(V.\) |
