A balloon full of air and an identical empty one — will they weigh the same? Ayesha says air has…

Why

Ayesha's belief comes from honest experience — you cannot feel air in your hand, and a balloon does not tug downward as you carry it, so weightless is a fair guess. But air is matter, made of particles with mass, and there are enormous numbers of them packed into every room: a single cubic metre of ordinary air weighs about 1.2 kilograms, roughly as much as a big bottle of water — and a room holds many, many cubic metres. It escapes your notice because the air around the balloon pushes up on it almost as hard as gravity pulls down, hiding nearly all of that weight. Picture the balloon as being weighed while sitting in an invisible sea. Test: balance two empty balloons on a stick, then inflate one — the inflated side dips, a little, but it dips. Tanvir is right: air has weight, and a fair test just has to be sensitive enough to show it.