**Pre-requisite**

Before putting hand on the problem, we should know that,

(1) 1 mm of Hg = 133 pascal

(2) If ‘d’ is the diameter of the cross-sectional area, then the area ‘A’ of the cross-section is given by,

A = πr^{2}

where ‘r’ is the radius of the cross-sectional area = d/2.