Heating the reaction flask on a hot plate is an example of supplying activation energy to begin a reaction.
Explanation:
<u>Definition:</u>
Activation energy is defined as the minimum amount of energy required to start a particular chemical reaction.
For example: When hydrogen and oxygen are mixed together it does not immediately start the reaction to form water. So, to start the reaction a small electric spark is provided or it is heated to provide some energy. This energy causes the molecules of hydrogen and water to react, thus producing even more molecules to react and finally water is formed.
Here the electric spark or the heat provided is the activation energy.
Granite is stronger, and it doesn't grow mold in the rain. It also looks better than marble and is easier to carve.
Number of moles : n₂ = 1.775 moles
<h3>Further explanation</h3>
Given
Moles = n₁ = 1.4
Volume = V₁=22.4 L
V₂=28.4 L
Required
Moles-n₂
Solution
Avogadro's hypothesis, at the same temperature and pressure, the ratio of gas volume will be equal to the ratio of gas moles
The ratio of gas volume will be equal to the ratio of gas moles

Input the values :
n₂ = (V₂ x n₁)/V₁
n₂ = (28.4 x 1.4)/22.4
n₂ = 1.775 moles
Whether water is frozen, in a gaseous state, or is a liquid, it is still H2O. So the chemical composition does stay the same.