Answer: It is very important to know the activity tendencies of the elements. The activity tendencies tells us about whether the element is reactive or not.
In the redox-reaction where there is a need to know the oxidizing agent and reducing agent, we can know it easily from the activity tendencies. The elements lying above the reactivity series are better reducing agents.
In the substitution reactions, the activity tendencies helps us to know which element will replace the other. The element lying above in the series will replace the element lying below it.

where, N is an element that lies above in the reactivity series
M is an element that lies below in the reactivity series
Answer:
What is the oxidation half reaction for iron?
The two elements involved, iron and chlorine, each change oxidation state; iron from +2 to +3, chlorine from 0 to -1. There are then effectively two half-reactions occurring. These changes can be represented in formulas by inserting appropriate electrons into each half-reaction: Fe2+ → Fe3+ + e.
Hope this helps..
An atom is the simplest particle that exists and retains the property of the element. A compound is made up of two or more elements chemically combined.
The net ionic equation is
Ag⁺(aq) +Cl⁻(aq) → AgCl(s)
Explanation
AgNO₃ (aq) + KCl (aq)→ AgCl(s) +KNO₃(aq)
from above molecular equation break all soluble electrolyte into ions
Ag⁺(aq) +NO₃⁻ (aq) + K⁺(aq) +Cl⁻(aq) → AgCl (s) + K⁺(aq) + No₃⁻(aq)
cancel the spectator ions in both side of equation =K⁺ and NO₃⁻ ions
The net ionic equation is therefore
= Ag⁺(aq) + Cl⁻(aq) → AgCl(s)
Before you begin titration, drops of indicator are added to the Erlenmeyer flask. This happens when preparing to measure pH change.