(1) The burning of white phosphorus releases heat, which increases the air volume in the test tube, so the balloon expands.

So the answer is: bloating.

(2) The red phosphorus in water can't burn mainly because the temperature of hot water can't reach the ignition point of red phosphorus and it doesn't contact with oxygen.

So the answer is: no ignition point, no exposure to oxygen.

(3) Chemical equation 4P+5O2 of white phosphorus combustion reaction? Light it? . ? 2P2O5, this reaction is a combination reaction in which two or more substances react to form another substance.

So the answer is: 4P+5O2? Light it? . ? Composite reaction of 2P2O5.