a) When the reaction takes place a yellow precipitate will be formed.
b) The law of conservation of mass is true.
<u>Explanation:</u>
a) When a lead nitrate solution is mixed with a potassium chromate solution, a yellow precipitate containing lead forms according to the equation:
→ 
b) Law of conservation of mass for the given reaction is true.
From the given table we know the mass of reactants and its products.
Law of conservation of mass is a principle when a reaction takes place in a closed system, the mass of the products and reactants in the system doesn't change.
⇒The sum of the mass of the reactants = The sum of the mass of the products.
The sum of the reactants = 128.71+128.97.
= 257.68 g.
The sum of the products = 154.10+103.58.
= 257.68 g.
Thus law of conservation of mass is true for the above reaction.
The answer is: emitted gas is carbon dioxide (CO₂).
Neutralization is is reaction in which an acid (in this example vinegar or acetic acid CH₃COOH) and a base (in this example soda)
Balanced chemical reaction of vinegar and antacid:
CH₃COOH(aq) + NaHCO₃(aq) → CH₃COONa(aq) + H₂O(l) + CO₂(g).
Sodium acetate (CH₃COONa) is a salt.
Sodium bicarbonate (NaHCO₃) is an antacid. Sodium bicarbonate is the active ingredient in baking soda.
The energy increases because the molecules in water move faster
Ca₁₀(PO₄)₆(OH)₂ - hydroxyapatite
b. phosphorus (P) and calcium (Ca)