The correct answer is option 1) (iii) 2KBr (aq) + Bal2(aq) → 2Kl(aq) + BaBr2(s)
potassium bromide (KBr) and barium iodide (BaI2) exchange ions to form potassium iodide (KI) and barium bromide (BaBr2). This reaction demonstrates the characteristic exchange of ions between two compounds, making it a double displacement reaction.
Ionic equation, focusing on the species that are involved in the chemical change:
2K+(aq) + 2I-(aq) + Ba2+(aq) + 2Br-(aq) → 2K+(aq) + 2I-(aq) + BaBr2(s)

Key Points

Additional Information Types of chemical reactions:
Example: 2H2(g) + O2(g) → 2H2O(l)
A single compound breaks down into two or more simpler substances.
General form: AB → A + B.
Example: 2H2O(l) → 2H2(g) + O2(g)
An element replaces another element in a compound, resulting in the formation of a new compound and a free element.
General form: A + BC → AC + B.
Example: Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) (zinc displaces hydrogen from hydrochloric acid).
The cations and anions of two different compounds exchange places to form new compounds.
General form: AB + CD → AD + CB.
Example: AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq) (formation of silver chloride and sodium nitrate).
Electrons are transferred between reactants. One substance loses electrons (oxidation), and another gains electrons (reduction).
Examples:
2Mg(s) + O2(g) → 2MgO(s) (oxidation of magnesium, reduction of oxygen).
Cu(s) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s) (oxidation of copper, reduction of silver ions).
A substance reacts rapidly with oxygen, usually producing heat and light.
Often involves hydrocarbons (compounds of hydrogen and carbon).
Examples:
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) (combustion of methane).
C6H12O6(aq) + 6O2(g) → 6CO2(g) + 6H2O(l) (combustion of glucose).
An acid reacts with a base to produce salt and water.
General form: Acid + Base → Salt + Water.
Example: HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) (neutralization of hydrochloric acid and sodium hydroxide).
Two soluble compounds in aqueous solution react to form an insoluble product (precipitate).
General form: AB(aq) + CD(aq) → AD(s) + CB(aq).
Example: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) (formation of lead iodide precipitate).