NCERT Solutions Curiosity Chapter 6 .3.4 What is soluble in water; what is not? — Activity 6.7: Let us explore
Book page 110 & 1116 Updated on2026-09-05
Q1.
Put a teaspoonful of sugar in the first glass tumbler, salt in the second one, chalk powder in the third, sand in the fourth and sawdust in the fifth glass tumbler. On stirring, predict what will happen in each case. Use a spoon to stir well the contents of each glass tumbler. Wait for a few minutes and watch what happens. Write down your observations in Table 6.5.
Answer
Fill five glass tumblers two-thirds with water, add one teaspoonful of each material, stir well and wait a few minutes.
Table 6.5: Mixing different materials in water
Material
Prediction — will / will not disappear in water
Observation — disappears / does not disappear
So the material is
Sugar
Will disappear
Disappears completely; water stays clear, tastes sweet
Soluble
Salt
Will disappear
Disappears completely; water stays clear, tastes salty
Soluble
Chalk powder
Will not disappear
Water turns milky; the powder slowly settles at the bottom
Insoluble
Sand
Will not disappear
Sinks straight to the bottom; water stays clear above it
Insoluble
Sawdust
Will not disappear
Floats on the surface even after long stirring
Insoluble
Any other — glucose powder
Will disappear
Disappears completely
Soluble
Any other — mustard oil
Will not disappear
Forms a separate layer on top
Insoluble
Materials that completely disappear are said to dissolve in water — they are soluble in water. Materials that do not mix and do not disappear even after long stirring are insoluble in water.
Fig. 6.6 in your book: what disappears in water, and what does not.
Why sugar “disappears”: it has not vanished — it has broken up into particles far too small for your eyes to see, and these have spread evenly through the whole of the water. That is why the water tastes sweet everywhere, and why boiling the water away leaves the sugar behind.
Did you know? Water dissolves a very large number of materials, which is why it plays such an important role in the working of our body — it carries dissolved food and wastes to every part.