In the gaseous state, the molecules are completely free because there is no intermolecular interaction between the molecules hence they translate at incredibly high velocity.
According to the kinetic theory of matter, the molecules that compose matter are in constant random motion. The nature of this motion varies in the three states of matter which are;
Solid
Liquid and
Gas
In the solid state, the molecules do not translate, they only vibrate and rotate about their mean positions. In the liquids state, the molecules translate but they still have restricted degrees of freedom due to intermolecular interactions. In the gaseous state, the molecules are completely free because there is no intermolecular interaction between the molecules hence they translate at incredibly high velocity.
One of the errors for low percentage of magnesium could be because not all the magnesium may have reacted.
Explanation:
During the heating process, if the magnesium have not reacted completely, it can lead to low percentage of magnesium in the oxide formed. The product may still look a bit greyish rather than whitish after the heating process.