Gases and the absolute scale of temperature

1 Describe qualitatively, in terms of particles, the effect on the pressure of a fixed mass of gas of:

(a) a change of temperature at constant volume

(b) a change of volume at constant temperature

2 Convert temperatures between kelvin and degrees Celsius; recall and use the equation

$$T\;\text{(in K)} = \theta\;\text{(in }{}^{\circ}\text{C)} + 273$$