An Explanation -
Why Ice Floats. A substance floats if it is less dense, or has less mass per unit volume, than other components in a mixture. For example, if you toss a handful of rocks into a bucket of water, the rocks, which are dense compared to the water, will sink. The water, which is less dense than the rocks, will float.
CH₄ + 2O₂ ---> CO₂ + 2H₂O
16g..................................18g×2
16g CH₄ --- 36g H₂O
5,1g CH₄ --- X
X = (5,1×36)/16
X = 11,475g H₂O
When hot food is placed inside the polymers it will melt, this is because there is weak attraction between polymer chains and thermosoftening so they melt and break away the bonds holding them together.