Question

The volume of 50 g of a substance is $20c{m}^3$. If the density of water is $1gc{m}^{-3}$, will the substance sink or float when placed on the surface of water ? What will be the mass of water displaced by the substance?
[4 Marks]

Answer 1

Density of the substance $=\frac{\text{Mass of the substance}}{\text{Volume of the substance}}=\frac{50}{20}gc{m}^{-3}$
$=2.5gc{m}^{-3}$
[1.5 Marks]

Density of water $=1gc{m}^{-3}$
If the density of an object is more than the density of a liquid, then it sinks in the liquid, otherwise, it floats.
Here the density of the substance is more than the density of water, so it will sink in water.
[1 Mark]

The volume of water displaced = Volume of substance = $20c{m}^3$
Mass of water displaced by substance = volume x density = 20 x 1 = 20 g.
[1.5 Marks]