Question

distinguish between displacement reaction and neutralisation reaction(double displacement reaction?

Answer 1

Displacement reaction
In a displacement reaction,a higher reactive element displaces a lower reactive element form it's ccompound.
Double displacement reaction
In this both the compound displaces one another.

Answer 2

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Single displacement reactions are reactions where one reactant replaces part of the other.

AB + C → AC + B

Double displacement reactions are reactions where the cations and anions in the reactants switch partners to form products.

AB + CD → AD + CB