Hi,

 

A tube of length h, which is wide enough to make surface tension effects negligible, is closed at one end. It is then lowered into a tank of mercury to a depth of 'h' as shown so that the mercury rises a distance 'x' into the tube. If the mercury barometer stands at 'h' also, then

 

(A) (2h-x)(h-x) = h²

(B) (2h-x)(h+x)=h²

(C) h(h-x)=h²

(D) 2h(h-x)=h²