The different weights of a piece of stone on weighing in three different media - air, fresh water and salt solution are given in the table. Answer the following questions by observing given table.

Medium	Weight
X	12 N
Y	18 N
Z	14 N

1. Identify water, air and salt solution among X, Y and Z
2. If the weight of 1kg mass in air is 10N, what will be the mass of the given stone?
3. Find the upthrust experienced by the stone?

1. Medium X is "salt solution", medium Y is "air" and medium Z is "water".


2. Solution
   Given
   Weight of the stone in air = 18N
   1 kg mass in air = 10N.
   1N = 1 ÷ 10 kg = 0.1kg
   So, 18N = 18 × 0.1 kg = 1.8 kg
   ∴ Weight of the stone = 1.8 kg.


3. Upthrust experienced by the stone in water = 18N - 14N = 4N
   Upthrust experienced by the stone in salt solution = 18N - 12N = 6N