The weight of a stone in three different media air, water, and solution of common salt is given.

A24 N
B28 N
C19 N

i. Which one is water and which one is air out of three media? Why?
ii. What is the mass of stone if 1 kg is equal to 10 N?

A is water and B is air out of three media because in the water there is medium weight due to the medium upthrust exerted by water whereas in the air there is maximum weight because of the least upthrust exerted by air.

In air media, 10 N = 1 kg
So, 28 N = 28 / 10 = 2.8 kg

Therefore, the mass of stone is 2.8 kg.