A chemical reaction is defined as the reaction between two or more substances that produces new substances/compounds.
On the other hand, a nuclear reaction is a reaction that alters the nucleus of a certain atom. This can be done either by splitting the nucleus or by joining this nucleus with another one.
Reaction 1:
Cl₂ + H₂ ............> 2 HCl
This is the combination of two elements to produce a new compound.
Therefore, this reaction is a chemical reaction
Reaction 2:
²₁H + ³₁H .........> ⁴₂H + ¹₀n
This is an alteration in the nucleus of a hydrogen atom by bonding it with another nucleus.
Therefore, this reaction is a nuclear reaction
Hope this helps :)
The finagling in the hole
The strength of an Arrhenius base determines percentage of ionization of base and the number of OH⁻ ions formed.
Strong base completely ionize in water and gives a lot of hydroxide ions (OH⁻), for example sodium
hydroxide: NaOH(aq) → Na⁺(aq)
+ OH⁻(aq).
Weak base partially ionize in water and gives a few hydroxide ions (OH⁻), for example ammonia: NH₃ + H₂O(l) ⇄ NH₄⁺(aq) + OH⁻(aq).