When people have stomach acidity, they take an antacid tablet and feel relief

Why

Vivaan's 'fight fire with fire' instinct is a real pattern that does show up elsewhere — sometimes you do treat a problem with more of the same. Here, though, the actual chemistry works the opposite way. The burning feeling comes from too much acid already sitting in the stomach, so adding more acid would only make that feeling worse, not better — the very name 'antacid' is a clue, meaning 'against acid.' What an antacid actually contains is a mild base (substances like magnesium hydroxide or calcium carbonate), which neutralises some of the stomach's excess acid the same way a base cancels an acid in a test tube, calming the burning by REDUCING the acid rather than adding to it. Test: an antacid tablet dropped into a cup of vinegar (a mild acid) will fizz and the mixture will measurably become less acidic — the exact reaction happening, on a larger scale, inside the stomach. No, antacid contains a base: it works by cancelling excess stomach acid, not by matching it — relief comes from neutralising the acid, not adding to it.