Question

The lengths of the air column in a capillary glass tube closed at one end containing mercury pellet 10cm long are 435 cm and 33.5 cm with the
and down respectively The atmospheric pressure is
(A) 72 cm
(B) 76 cm
(C) 77 cm
(D) 75 5 cm​

Answer 1

Answer:

Let the air pressure be x cm of hg. Hence if bottle faces up , the air pressure of 33 cm air is x+ 10 and when placed down, 43 cm has x - 10. The volumes are 33A and 43A where A is the area of the test tube. Assuming isothermal process, 33A(x+10)=43A(x−10)

⟶x=76cm