<u>Answer:</u>
A reaction is said to occur if there is a formation of an insoluble solid or a precipitate(s) or a liquid (l) or a gas(g).
If both the reactants and products are in aqueous state, No reaction takes place.
All chlorides and Bromides are soluble except that of Ag, Hg and Pb.
Hence, No reaction takes place since all the reactants and products are in aqueous states.
Salts of Group IA are soluble. Hence No reaction takes place
(REACTION TAKES PLACE)
All hydroxides are insoluble except that of Group IA, ammonium ion and Group IIA down from Calcium.
Hence Reaction takes place with the formation of 
precipitate
K₃PO₄ → 3K⁺ + PO₄³⁻
PO₄³⁻ + H₂O ⇄ HPO₄²⁻ + OH⁻
HPO₄²⁻ + H₂O ⇄ H₂PO₄⁻ + OH⁻
H₂PO₄⁻ + H₂O ⇄ H₃PO₄ + OH⁻
K⁺, PO₄³⁻, HPO₄²⁻, H₂PO₄⁻, OH⁻
The coefficients are 1 : 2 : 1 : 1
<u>Explanation:</u>
To be a balanced equation, the chemical equation should have has equal number of atoms on both reactant and product side.
Given chemical equation:
Now, calculate the number of atoms present in reactant side:
Sn - 1
- 1
K - 1
Br - 1
Then, calculate the number of atoms present in product side:
Sn - 1
- 1
K - 2
Br - 2
Therefore, in order to balance this given chemical equation multiply KBr by 2 on reactant side. So, the balanced chemical equation is as follows.
Hence,
Answer: A physical change is a change that can be undone.
Explanation: An example of this is mixing red blocks, green blocks, and blue blocks. You can easily separate them.
