Q. An adulterated sample of milk has density of $1032\ kg\ m^{- 3}$, while pure milk has a density of $1080\ kg\ m^{- 3}$. Then the volume of pure milk in a sample of 10 L of adulterated milk is

A) 0.5 L
B) 1.0 L
C) 2.0 L
D) 4.0 L
Explanation

(d) Mass of adulterated milk
$M_{A} = 1032 \times 10 \times 10^{- 3}$
$= 10.32\ kg\ \ \ \ \ \ \ \ \ \ \ \ $
Mass of pure milk $\ \ M_{p} = 1080V_{p}$
$\therefore\ \ \ \ \ \ \ Mass\ of\ water\ \rho_{w}V_{w} = M_{A} - M_{p}$
$\Longrightarrow \ \ 10^{3}\left( 10 \times 10^{- 3} - V_{p} \right) = 10.32 - 1080V_{p}$
$\Longrightarrow \ 10 - 10^{3}V_{p} = 10.32 - 1080V_{p}$
$\Longrightarrow \ \ 80V_{p} = 0.32$
$\therefore\ \ V_{p} = \frac{0.32}{80}m^{3}$
$= \frac{0.32}{80} \times 1000L = 4L$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.