Cold water weighs more than hot water.

if you have the same temperature water, then take 2 cups of water, put one in fridge, put one in the hot sun, they weigh the same, but they will be different heights in the cup, because cold water compresses and hot water expands. this fact is saying that if cold water is put into a cup, and hot water is put into a cup then they will be different weights which is true because more water will be able to fit in the cold cup and less water in the hot cup. so in the format this statement is in, this is false.

In terms of density your correct, may i correct you on another, though just my own theroy? A pice of ice floats in water due to its lower density then water, therefore it would not weigh more, now in the case of water, the molacules in the water will compress, thus makeing it weigh more, but not have more mass. Mass and weight are diffrent.

Water that is 4 C have higher density then anyother water in anyother tempeture.

As "Breaker" said, water is at its heaviest at 4C. X volume of water at 4C is heavier than the same volume of 20C water.

statement is false.

duh if u put 2 cups same weight one in fridge and one under the sun, of course the one under the sun is going to weight less sun is going to evaporate half of the cup,, FALSE

Obviously, water at 4 °C weighs the most, as the density of water is at its maximum...