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List of practice Questions

Which of the following are chemical changes?
(a) Growth of a plant
(b) Rusting of iron
(c) Mixing of iron filings and sand
(d) Cooking of food
(e) Digestion of food
(f) Freezing of water
(g) Burning of a candle
  • CBSE Class IX
  • Science
  • Physical and Chemical Changes

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 nitrate213262106167
Sodium chloride3636363737
Potassium chloride 3535404654
Ammonium chloride2437415566

 

(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?

  • CBSE Class IX
  • Science
  • Physical and Chemical Changes
How would you confirm that a colorless liquid given to you is pure water?
  • CBSE Class IX
  • Science
  • Physical and Chemical Changes