Q 11-09-012NEETJEE MainMedium
A U-tube contains water. Oil is poured into one arm until the oil column is $12$ cm long, while the water level in the other arm stands $10$ cm above the oil–water interface. The density of the oil is about
Answer: (C) $833$ kg m$^{-3}$
Concept. Pressures are equal at the level of the oil–water interface in both arms.
Step 1. Balance. $\rho_{\text{oil}} \times 12 = 1000 \times 10$.
Step 2. Solve. $\rho_{\text{oil}} \approx 833$ kg m$^{-3}$.
Answer. $833$ kg m$^{-3}$ (Option C).
Solution by Sreeraj P, M.Sc Physics