Priya says if you mix any acid and any base in any amounts, the result will always be exactly…

Why

Priya has correctly learned that acids and bases cancel each other out — that idea, called neutralisation, is genuinely how the reaction works, and mixing them really does move the result towards neutral. Where the rule needs a second half is realising that 'moving towards neutral' only lands EXACTLY on neutral when the amounts are balanced just right. Pour a large amount of a strong acid into a tiny bit of a mild base, and the acid has far more than enough to cancel the base and still have plenty left over — the result stays acidic, just less acidic than before. The reverse is true too: too much base overwhelms a small amount of acid and leaves the mixture basic. Only when the acid's and base's strengths are matched in careful amounts does the mixture land precisely on neutral. Test: add a few drops of a base to a large glass of acidic lemon juice and test with litmus — it will still read acidic, just slightly less strongly than before any base was added. The teacher is right: mixing an acid and a base moves the result towards neutral, but the exact outcome depends on how much of each was used, not just that both were present.