The volume of a given mass M varies directly as it's temperature and inversely as it's pressure.if the volume is 30cm when it's temperature is 10k and pressure is 40mmHg, calculate:

(I) the constant of proportionality
(Ii) the formula connecting them
(Iii) the pressure when the volume is 50cm and temperature 2k

(I) To find the constant of proportionality, we can use the formula V = kT/P and plug in the given values:

30 = k(10)/40
k = 120

Therefore, the constant of proportionality is 120.

(Ii) The formula connecting M, T, and P is V = kT/P.

(Iii) To find the pressure when the volume is 50cm and temperature is 2k, we can again use the formula V = kT/P:

50 = 120(2)/P
P = 48/5 mmHg

Therefore, the pressure when the volume is 50cm and temperature is 2k is 48/5 mmHg.