Question

If a constant volume gas thermometer records a pressure of 20 kPa at tripple point of water and pressure of 14.3 kPa at the dry ice, then the temperature of dry ice will be

• A. $ -77.85{}^\circ C $
• B. $ +77.85{}^\circ C $
• C. $ -66.05{}^\circ C $
• D. None of these

Answer 1

Answer: (A)

Given, $ {{p}_{T}}=20.0\,kPa $
and $ p=14.3\text{ }kPa $
By the relation, $ T=(273.16K)\left( \frac{p}{{{p}_{T}}} \right) $
$ =(273.16K)\times \left( \frac{14.3kPa}{20.0kPa} \right)=195.3K $
On celsium scale $ \theta ({}^\circ C)=T(K)-273.15K $
$ =195.3-273.15 $
$ =-77.85{}^\circ C $