Q 11-09-014NEETJEE MainMedium
A wooden block floats in water with $\dfrac{2}{3}$ of its volume submerged. In a liquid X it floats with $\dfrac{5}{6}$ of its volume submerged. The density of liquid X is
Answer: (A) $800$ kg m$^{-3}$
Concept. Fraction submerged $= \dfrac{\rho_{\text{block}}}{\rho_{\text{liquid}}}$.
Step 1. Block density. $\dfrac23 \times 1000 \approx 667$ kg m$^{-3}$.
Step 2. Liquid X. $\rho_X = \dfrac{667}{5/6} = 800$ kg m$^{-3}$.
Answer. $800$ kg m$^{-3}$ (Option A).
Solution by Sreeraj P, M.Sc Physics