Pooja boils milk and leaves it covered on the table, saying it will not spoil now because boiling…

Why

Pooja is correct about the first half, and it is the half that matters most: boiling really does kill the microorganisms in the milk at that moment, which is exactly why we boil it. Where the reasoning slips is in treating that as permanent. Killing what is present does nothing about what arrives afterwards — every time the lid lifts, and even through the gap around it, new spores settle in. Warm milk is close to the perfect food for them, so a few become millions within hours. Cold does not kill them; it just slows them down so much that the milk keeps for days. Test: boil milk twice and leave one pot out and one in the fridge — the outside pot still turns by evening. Irfan is right: boiling clears what is there now, refrigeration handles what comes next, and the two do different jobs.