Question

A sample of metal weighs 210 gm in air, 180 gm in water and 120 gm in liquid. Then relative density (RD) of

• A. Metal is 3
• B. Metal is 7
• C. Liquid is 3
• D. Liquid is

Answer 1

Answer: (B), (C)

The correct options are
B Metal is 7
C Liquid is 3

Let the density of metal is $\rho$ and density of liquid is $\sigma$.
If V is the volume of sample then according to problem
$210=V\rho g\dots \left(1\right)180=V(\rho -1)g\dots \left(ii\right)120=V(\rho -\sigma )g\dots \left(iii\right)$
By solving (i), (ii) and (iii) we get $\rho =7and\sigma =3$