A gas escapes from an open container because it has no weight. The Kelvin is a unit of volume. Sodium chloride dissolves in water to form a solution which conducts electricity. Oxygen is denser than water. When an electric current is passed through water, an endothermic reaction occurs and two volumes of hydrogen and one volume of oxygen are formed.
Most soft drinks contain the element sodium which is a shiny silvery metal.
Calcium carbonate is a solid mixture. A conducting material contains charged particles which are free to move. When water boils, hydrogen and oxygen gas are formed. The gaseous elements are nonmetals and do not conduct electricity. The actual density could be determined by measuring the fraction of the ship that is under water.