Select all that apply. which of the following statements about boyle's law are correct? the temperature and pressure must remain constant for the law to apply. the temperature and the number of molecules must remain constant for the law to apply. as the pressure of a gas increases, the volume increases proportionally. as the pressure of a gas increases, the volume decreases proportionally.

Boyle's law states that the relationship between pressure and volume of a fixed amount of gas at a fixed temperature is inversely proportional. This means that the higher the pressure, the lower the volume, in a proportional relationship. Therefore, of the statements listed, b: 'the temperature and the number of molecules must remain constant for the law to apply' and d: 'as the pressure of a gas increases, the volume decreases proportionally' are correct.

The answer is option b.