Q. A U-tube having horizontal arm of length 20 cm, has uniform cross-sectional area = 1 sq. cm. It is filled with water of volume 60 cc. What volume of a liquid of density 4 g/cc should be poured from one side into the U-tube so that no water is left in the horizontal arm of the tube?
A. 60 cc
B. 45 cc
C. 50 cc
D. 35 cc