Question

The mass of a stone is 15.0g when completely immersed in water and 10.0 when completely immersed in a liquid of relative density 2.0 what is the mass of the stone in air.

Answer 1

mass does not change. Apparent mass might change.

The mass of the stone is 15g, in air, under water, or on the moon.

Answer 2

Mass of a particular solid in a particular fluid, air or liquid, does not change as bobpursley posted, but it does change when the fluid is changed. A stone when weighed in air, water, diesel, brine, etc would give different values because of the different densities or viscosities of the fluids. But the stone weighs the same thing in each of the fluids anywhere in the world,i.e. on the planet earth.