Class 10 Study of Compounds: Hydrogen Chloride Mock Test (ICSE)

Topics in Study of Compounds: Hydrogen Chloride

• Preparation of hydrogen chloride
• Properties of hydrogen chloride
• Fountain experiment
• Hydrochloric acid and its reactions

Study of Compounds: Hydrogen Chloride practice questions with answers

1. Q1Multiple choice·1 mark
   Which of the following observations is correct when a glass rod dipped in concentrated ammonia solution is brought near the mouth of a jar containing hydrogen chloride gas?

   1. (a)A pale green gas is evolved with an effervescence.
   2. (b)A white precipitate of calcium chloride is formed.
   3. (c)Dense white fumes of ammonium chloride are produced.
   4. (d)No visible reaction takes place.
   Show answer and step marks

   1. Correct option: (c) Dense white fumes of ammonium chloride are produced.+1

   Answer: (c)
2. Q2Multiple choice·1 mark
   When concentrated hydrochloric acid is heated with manganese dioxide, the greenish-yellow gas evolved is:

   1. (a)Hydrogen
   2. (b)Oxygen
   3. (c)Chlorine
   4. (d)Hydrogen chloride
   Show answer and step marks

   1. Correct option: (c) Chlorine+1

   Answer: (c)
3. Q3Multiple choice·1 mark
   During the fountain experiment using hydrogen chloride gas, if a few drops of methyl orange indicator are added to the water in the trough, the colour of the fountain produced inside the flask is:

   1. (a)Colourless
   2. (b)Blue
   3. (c)Yellow
   4. (d)Pink or red
   Show answer and step marks

   1. Correct option: (d) Pink or red+1

   Answer: (d)
4. Q4Multiple choice·1 mark
   In the laboratory preparation of hydrogen chloride gas, the drying agent generally used is:

   1. (a)Alkaline pyrogallol
   2. (b)Calcium oxide
   3. (c)Fused calcium chloride
   4. (d)Concentrated sulphuric acid
   Show answer and step marks

   1. Correct option: (d) Concentrated sulphuric acid+1

   Answer: (d)
5. Q5Long answer·4 marks
   With reference to the fountain experiment used to demonstrate the properties of hydrogen chloride gas: (a) State the property of hydrogen chloride gas that is primarily demonstrated by this experiment. (b) If the water introduced into the flask contains a few drops of blue litmus solution, state the colour change observed in the resulting fountain and give a reason for it. (c) Mention two essential conditions necessary for the successful demonstration of this fountain experiment.
   Show answer and step marks

   1. (a) Hydrogen chloride gas is extremely (highly) soluble in water.+1
   2. (b) The fountain is red: blue litmus turns red.+0.5
   3. (b) Reason: hydrogen chloride dissolves in water to form hydrochloric acid, and the acid turns blue litmus red.+0.5
   4. (c) First condition, any one of: the round-bottomed flask must be completely dry; the flask must be completely filled with dry hydrogen chloride gas; the apparatus must be airtight; the jet tube must be narrow and dip into the water in the trough; or any other valid condition.+1
   5. (c) Second condition, a different one from the same list.+1

   Answer: (a) HCl gas is highly soluble in water. (b) The fountain is red, because HCl dissolves to form hydrochloric acid, which turns blue litmus red. (c) Any two of: the flask must be completely dry; the flask must be filled with dry HCl gas; the apparatus must be airtight; the jet tube must be narrow and dip into the water.
6. Q6Long answer·4 marks
   With reference to the fountain experiment demonstrated with hydrogen chloride gas, answer the following questions: (a) State the specific property of hydrogen chloride gas demonstrated by this experiment. [1] (b) If the water entering the flask contains blue litmus solution, state the colour of the fountain formed and give a scientific reason for the observed colour change. [2] (c) Why is it essential that the round-bottomed flask is completely dry and filled with hydrogen chloride gas before starting the experiment? [1]
   Show answer and step marks

   1. (a) High solubility of hydrogen chloride gas in water.+1
   2. (b) Colour: the fountain is red (the blue litmus turns red).+1
   3. (b) Reason: hydrogen chloride dissolves in water to form hydrochloric acid, which furnishes hydronium ions ($H_3O^+$); being acidic, it turns blue litmus red.+1
   4. (c) Any one of: the flask must be dry because HCl is highly soluble in water, so any moisture would dissolve the gas beforehand and spoil the experiment; or it must be completely filled with HCl (no air) so that when the gas dissolves, a rapid and complete pressure drop (partial vacuum) is created that draws the water up as a fountain; or any other valid reason.+1

   Answer: (a) HCl gas is extremely soluble in water. (b) The fountain is red: HCl dissolves to form hydrochloric acid, which gives $\text{H}_3\text{O}^+$ ions that turn blue litmus red. (c) HCl is so soluble that moisture in the flask would dissolve the gas beforehand; a dry flask completely full of HCl lets the gas dissolve suddenly, creating a partial vacuum that draws the water up as a fountain.

More Class 10 Chemistry mock tests