A vertical U-tube of uniform inner cross section contains mercury in both sides of its arms. A glycerine (density = l.3 g/${\mathrm{cm}}^3$) column of length 10 cm is introduced into one of its arms. Oil of density 0.8 gm/${\mathrm{cm}}^3$ is poured into the other arm until the upper surfaces of the oil and glycerine are in the same horizontal level. Find the length of the oil column, (Density of mercury = 13.6 g/${\mathrm{cm}}^3$).

 

• A

  10.4 cm

• B

  8.2 cm

• C

  7.2 cm

• D

  9.6 cm