Question

Find the densities of these substances from the given data. The make a list of the substances that will float on a. water, b. kerosene, c, mercury.
Figure

Answer 1

According to the figure given and the formula Density = Mass / Volume,
we can find the following.

The density of water = 7 g / 7 ml
= 1 g/ml
= 1 g/cm³

The density of iron = 39.5 g / 5 cm³
= 7.9 g/cm³

The density of glass = 10 g / 4 cm³
= 2.5 g/cm³

The density of ice = 4.5 g / 5 cm³
= 0.9 g/cm³

The density of aluminium = 21.6 g / 8 cm³
= 4.32 g/cm³

The density of cork = 4 g / 10 cm³
= 0.4 g/cm³

The density of mercury = 40.5 g / 3 ml
= 13.5 g/ml = 13.5 g/cm³

The density of kerosene = 7 g / 10 ml
= 0.7 g/ml = 0.7 g/cm³

We know that if the density of a small substance is less than the density of a liquid, then it floats on the liquid. If not, it sinks in the liquid.
So, the substances that will float on water are ice and cork.
The substances that will float on kerosene are ice and cork.
The substances that will float on mercury are iron, glass, ice, aluminium and cork.