Two ideal gas thermometer `A` and `B` use oxygen and hydrogen respectively . The following observations are made:
Temperature, Pressure therometer A, Pressure therometer B
Triple point of water, `1.250xx10^(5)Pa`, `0.200xx10^(5)Pa`
Normal melting point of sulphur, ` 1.797xx10^(5)Pa`, `0.287xx10^(5)Pa`
(a) What is the absolute temperature of normal melting point of sulphur as read by thermometers `A` and `B` ?
(b) What do you think is the reason for the slightly different answers from `A` and `B` ? (The thermometers are not faulty). what further procedure is needed in the experiment to reduce the discrepancy between the two readings.

Explanation

(a) Let T be the melting point of sulphir. For water, `T_(tr) = 273.16K`
For thermometer `A` `T = (P)/(P_(tr)) xx 273.16 = (1.797xx10^(5))/(1.250xx10^(5)) xx 273.16 = 392.69K`
For thermometer `B` `T = (P)/(P_(tr))xx273.16 = (0.287xx10^(4=5))/(0.200 xx10^(5)) xx 273.16 = 391.98K`
(b) The cause of slight different answers is that the oxygen and hydrogen gases are not perfectly ideal. To reduce this discrepancy, the reading should be taken at lower and lower pressure as in that case, the gases approch to the ideal gas behaviour.