Mass is just "the amount of stuff there is". We can measure it in kg. If I have 4kg ice and 4kg water, then the answer is "no", but I could just as easily have 4kg of ice and 5kg water, in which case the answer is "yes". If you mean "does freezing water make it heavier?", then the answer is no - 4kg water makes 4kg ice, and they will weigh the same. However, ice has a greater volume than water*, so freezing water will make it expand. *This is not true for every liquid/solid combo.
4kg is 141.096 ounces.
It is: 5kg-1kg = 4kg
Assuming density of 1g/ml, 4 litres
4kg = 0 stone 8.8lbs
4kg is the equivalent of 8.82pds.
4kg = 4,000g, so 4kg is greater than 513g