Explanation:
Tollens' reagent is prepared by using two-step process : -
Step 1:
Silver oxide is formed by mixing aqueous silver nitrate with base like sodium hydroxide. The reaction is shown below as:

Step 2
Ammonia solution is drop-wise added until all the silver oxide dissolves to form the reagent. The reaction is shown below as:

The solution changed color because the substances are not neutral.
<h3>
pH</h3>
Chemical substances have different concentrations of the hydrogen cation, called PH.
The higher the pH, the more basic the substance, and the lower the more acidic.
Bromothymol blue is a pH indicator that changes its color according to the pH of the substance, yellow for acid, blue for basic and green for neutral.
In the case of the reactions in question, we have the release of CO2 (acid) in combustion and in cellular respiration, changing the color of bromothymol blue to yellow.
Learn more about pH in: brainly.com/question/491373
Answer:
Evaporation is the method of separating a solid (solute) from a homogeneous solution.
in this method, the solution is heated until the solvent gets evaporated in the form of vapor and the solute is left behind as residue.
Aluminum has a chemical formula of Al, while diatomic bromine has a chemical formula of Br₂. The balanced chemical reaction is shown below:
<em>2 Al (s) + 3 Br₂ (l) → 2 AlBr₃ (s)</em>
The solid product is called Dibromoaluminum. The stoichiometric coefficients are used to balance the reaction to obey the Law of Conservation of Mass.