Question

Why 0 is additive identity of all rational

Answer 1

0 is additive identity of all rational numbers because if we add 0 to any rational number, the number is the same, and so is its identity.

Answer 2

0 is the additive identity for all rational numbers as if we add 0 to a rational number the sum will always be the number itself
for example let the rational number be 1 then 1+0=0
(hope this helps)