Answer :
Answer:
1) Wood
2) Water
3) Helium
4) Oil
Explanation:
In order to compare the densities in each pairt, let's have a look at the values of the density for each substance/material.
1) Wood vs water
Density of wood is variable, between [tex]0.2 g/cm^3[/tex] and [tex]1.0 g/cm^2[/tex] depending on the type of wood, while density of water is [tex]1.0 g/cm^3[/tex]: therefore, wood is less dense than water.
2) Steel vs water
Density of steel is around [tex]8-9 g/cm^3[/tex], while that of water is [tex]1.0 g/cm^3[/tex], so water is less dense than steel
3) Helium or air
Helium density is (at standard temperature and pressure) around [tex]9\cdot 10^{-5} g/cm^3[/tex], while the air density is about [tex]0.001 g/cm^3[/tex], so helium is less dense than water.
4) Oil or water
Oil density is around [tex]0.93 g/cm^3[/tex], while water is [tex]1.0 g/cm^3[/tex], so oil is less dense than water.
We can also use another method to compare the densities, without knowing their exact value. In fact, a substance 1 which is less dense than a substance 2 will float in substance 2, otherwise it will sink.
From common experience, we know that:
- Wood floats in water, so wood is less dense than water
- Steel sinks in water, so water is less dense than steel
- Helium floats in air (a helium balloon goes up), so helium is less dense than water
- Oil floats in water, so oil is less dense than water