These phases are liquid, solid, gas.
Sink.
The most common thing that would be a gram is a mL of water. That is, it is waters maximum density, temperature and purity will change that.
Salinity (how much salt) of the water and low temperatures
Oil is heavier than water so it sinks to the bottom.
An object will sink if its density is greater than the fluid it is placed in, and it will float if its density is less than the fluid. Density is a measure of how much mass is contained in a given volume, so comparing the density of an object to the density of the fluid it is in helps predict its buoyancy.
Density
Lower.
The temperature of the water and the salt content of the water.
Saturn, because it's density is less than that of waters.
The Antarctic Intermediate Water (AAIW) are the low salinity waters found in the Southern Ocean.
'Unknown' is an adjective, 'waters' is a common noun. Possibly the expression is the title of something in particular that you meant, in which case you should have capitalised it.
The attraction from the moon, and less from the sun, causes the waters of the world to form the tides of flood and ebb.