there are 2 samples of water labelled as 'a' and 'b' . a boils at 100ºc and b boils at 102ºc. which sample will not freeze at 0ºc ?
Sample 'b' will freeze at a temperature lower than 0oc. This is because it is not pure water, it contains some solute in it which causes elevation in boiling point and depression in freezing point