Answer:
Learn from their experiment and know the possible results from trial and error
Air pressure is measured with a barometer.
Chemical equation is the symbolic representation of chemical reactions.
Explanation
Chemical reactions are known as the reaction where two or more molecules or compounds react with each other leading to formation of product compounds along with either release or absorption of energy.
The symbolic representation of the processes occurring in a chemical reaction is termed as chemical equation.
The symbolic representation includes the reactants, products, external energy type and quantity of external energy and also about release of energy if occurs.
So the reactants are usually written in the left side of the chemical equation whereas on the right the products are written.
Both the sides are linked by a single headed arrow mark.
Some both the sides are linked by double heated arrow mark indicating the equilibrium chemical reaction.
Their weights could be different.
Their volumes could be different.
Their densities could be different.
The volume for an ounce of lead is much different than an ounce of aluminum.
the weight of a cubic meter of balsa wood is much different (and much lighter) than a cubic meter of water. That's why the ancients used balsa for their rafts.