the standard substance is pure water. Simply put the values in the specific gravity equation to know the answer. Specific Gravity = = = 12. So the density of the object is 12 g/mL and the specific gravity is 12. Hence the density of the material and that of the water must be expressed in the same units. Solved …Specific gravitygases: 1)NTP - Normal Temperature and Pressure- is defined as 20oC (293.15 K