A U-tube with both ends open to the atmosphere is partially filled with water. Oil, which is immiscible with water. Is poured into one side until it stands at a distance of `10 mm` above the water level on the other side. Meanwhile the water rises by `65mm` from its original level (see diagram). The density of the oil is:

Options

A. `425kg m^(-3)`
B. `800 kg m^(-3)`
C. `928 kg m^(-3)`
D. `650 kg m^(-3)`

Answer

C

Explanation

`P_(B) = P_(C )` (pressure at same level is same) [Pascal law]
`H rho_("oil")g= h rho_(w) g`
`(65 + 65 + 10) xx 10^(-3) xx rho_(0)= (65+65) xx 10^(-3) xx 10^(3)`
`140 rho_(B)= 130 xx 10^(3)`
`rho_(B)= (130)/(140) xx 10^(3)`
`rho_(0) 928 kg m^(-3)` (approx)