Gas Trapped in a Capillary Tube - Example 1

Example 1:

Figure above shows 3 identical capillary tubes with one end sealed and containing a column of mercury. PA, PB and PC are the gas pressure in the capillary tubes respectively. Find the value of PA, PB and PC. [Atmospheric pressure = 76cmHg]


P= 76cmHg

PB = 76cmHg + 2cmHg = 78cmHg

P= 76cmHg - 2cmHg = 74cmHg