Which of the following is true with regard to Gay Lussac's law?
1
At constant temperature, pressure of a fixed amount of gas is inversely proportional to its volume.
2
At constant volume, pressure of a fixed amount of gas varies directly with temperature.
3
At constant pressure, volume of a fixed mass of gas is directly proportional its absolute temperature.
4
It is a gas law which combines Charles's law and Boyle's law.