Page 34 - Understanding NCERT Science 09

2. Write the steps you would use for making tea. Use the words
solution, solvent, solute, dissolve, soluble, insoluble, filtrate
and residue.
3. Pragya tested the solubility of three different substances at
different temperatures and collected the data as given below
(results are given in the following table, as grams of substance
dissolved in 100 grams of water to form a saturated solution).

Substance Dissolved Temperature in K
283 293 313 333 353
Solubility

Potassium nitrate 21 32 62 106 167
Sodium chloride 36 36 36 37 37

Potassium chloride 35 35 40 46 54
Ammonium chloride 24 37 41 55 66

(a) What mass of potassium nitrate would be needed to
produce a saturated solution of potassium nitrate in
50 grams of water at 313 K?
(b) Pragya makes a saturated solution of potassium chloride
in water at 353 K and leaves the solution to cool at
room temperature. What would she observe as the
solution cools? Explain.
(c) Find the solubility of each salt at 293 K. Which salt has
the highest solubility at this temperature?
(d) What is the effect of change of temperature on the
solubility of a salt?
4. Explain the following giving examples.
(a) Saturated solution
(b) Pure substance
(c) Colloid
(d) Suspension
5. Classify each of the following as a homogeneous or
heterogeneous mixture.
soda water, wood, air, soil, vinegar, filtered tea.
6. How would you confirm that a colourless liquid given to you
is pure water?

IS MATTER AROUND US PURE? 23

Rationalised 2023-24