Question

explain explain explain explain​

Answer 1

ANSWER : 1)

because it can't be reversed.

irreversible in the sense, it's not reversible..

some resultants/products can be turned back into the reactants through a process. those are reversible equations. some just can't, those are irreversible.

Answer 2

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2, 3, 4 are reversible whereas 1st is irreversible.