18 + Interview Questions in PRACTICAL CHEMISTRY IN GENERAL AWARENESS

1.	Give a chemical test to distinguish between the Lead chloride and lead sulphide.
Answer» Added MnO₂ and cone. H₂SO₄ to the salt Lead Chloride and heat it. A greenish coloured yellow coloured gas with punget odour is evolved which turns moist starch iodide paper blue black. Now add dil. H₂SO₄ to Lead sulphide and heat Colourless gas with rotten egg smell is evolved. The gas evolved turns moist lead acetate paper silvery black.

1.

Give a chemical test to distinguish between the Lead chloride and lead sulphide.

Answer»

Added MnO₂ and cone. H₂SO₄ to the salt Lead Chloride and heat it.

A greenish coloured yellow coloured gas with punget odour is evolved which turns moist starch iodide paper blue black.

Now add dil. H₂SO₄ to Lead sulphide and heat

Colourless gas with rotten egg smell is evolved. The gas evolved turns moist lead acetate paper silvery black.

2.	Select the gas that has a charateristic rotten egg smell. [ammonia, ethane, hydrogen chloride, hydrogen sulphide, ethyne].
Answer» Hydrogen sulphide.

Discussion

3.	State your observation : When moist starch iodide paper is introduced into chlorine gas.
Answer» The starch iodide paper turns blue due to the liberation of free iodine.

Discussion

4.	Gas Q turns moist lead acetate paper silvery black. Identify the gas Q. pH of liquid R is 10. What kind of substance is R?
Answer» The gas Q is H₂S (Hydrogen sulphide). The substance R is a alkaline.

4.

Gas Q turns moist lead acetate paper silvery black. Identify the gas Q. pH of liquid R is 10. What kind of substance is R?

Answer»

The gas Q is H₂S (Hydrogen sulphide).

The substance R is a alkaline.

Discussion

5.	State one relevant observation : When hydrogen sulphide gas is passed through lead acetate solution.
Answer» When hydrogen sulphide gas is passed through lead acetate solution, it forms a black precipitate of lead sulphide.

Discussion

6.	State your observation – 1. A piece of moist blue litmus paper 2. Paper soaked in potassium permanganate solution- is introduced into a gas jar of sulphur dioxide.
Answer» 1. Moist blue litmus turns red and finally colourless as SO₂ act as an acidic gas and then a bleaching agent. 2. The pink colour of potassium permanganate paper turns colourless because of bleaching property of sulphur dioxide.

6.

State your observation – 1. A piece of moist blue litmus paper 2. Paper soaked in potassium permanganate solution- is introduced into a gas jar of sulphur dioxide.

Answer»

1. Moist blue litmus turns red and finally colourless as SO₂ act as an acidic gas and then a bleaching agent.

2. The pink colour of potassium permanganate paper turns colourless because of bleaching property of sulphur dioxide.

Discussion

7.	How will the addition of barium chloride soln. help to distinguish between dil. HCl and dil. H2SO4 .
Answer» Barium chloride does not react with dil HCl but with dil H₂SO₄ gives a white ppt. of barium sulphate.

Discussion

8.	From the list of substances given—Ammonium sulphate, Lead carbonate, Chlorine, Copper nitrate, Ferrous sulphate — State : A substance that turns moist starch iodide paper blue.
Answer» The list of substances Lead carbonate Chlorine.

Discussion

9.	Write the equation for the reaction of magnesium sulphate solution with barium chloride solution.
Answer» MgSO₄ + BaCl₂ → BaSO₄ + MgCl_2.

Discussion

10.	Choose from the list of substances – Acetylence gas, aqua fortis, coke, brass, barium chloride, bronze, platinum. An aqueous salt solution used for testing sulphate radical.
Answer» Barium chloride.

Discussion

11.	Identify the anion present in the following compounds : 1. Compound X on heating with copper turnings and concentrated sulphuric acid liberates a reddish brown gas. 2. When a solution of compound Y is treated with silver nitrate solution a white precipitate is obtained which is soluble in excess of ammonium hydroxide solution. 3. Compound Z which on reacting with dilute sulphuric acid liberates a gas which turns lime waer milky, but the gas has no effect on acidified potassium dichromate solution. 4. Compound L on reacting with Barium chloride solution gives a white precipitate insoluble in dilute hydrochloric acid or dilute nitric acid.
Answer» 1. Nitrate ion, NO^{3 –} 2. Chloride ion, Cl^– 3. Carbonate ion, CO₃^2- 4. Sulphate ion, SO₄

11.

Identify the anion present in the following compounds : 1. Compound X on heating with copper turnings and concentrated sulphuric acid liberates a reddish brown gas. 2. When a solution of compound Y is treated with silver nitrate solution a white precipitate is obtained which is soluble in excess of ammonium hydroxide solution. 3. Compound Z which on reacting with dilute sulphuric acid liberates a gas which turns lime waer milky, but the gas has no effect on acidified potassium dichromate solution. 4. Compound L on reacting with Barium chloride solution gives a white precipitate insoluble in dilute hydrochloric acid or dilute nitric acid.

Answer»

1. Nitrate ion, NO^{3 –}

2. Chloride ion, Cl^–

3. Carbonate ion, CO₃^2-

4. Sulphate ion, SO₄

Discussion

12.	Give a reason why carbon dioxide and sulphur dioxide cannot be distinguished by using lime water.
Answer» Because both turns lime water milky.

Discussion

13.	Give one test each to distinguish between the following pairs of chemicals solutions 1. Zn(NO3)2 and Ca(NO3)2 2. NaNO3 and NaCI 3. Iron [III] chloride and copper chloride.
Answer» 1. Add NaOH solution in excess to the two solutions. The one in which white ppt. initially formed dissolves in excess of NaOH solution is Zn(NO₃)₂ solution and the other is Ca(NO₃)₂ solution. 2. Add freshly prepared ferrous sulphate solution to the two solutions. Then by the side of the test tube, pour cone, sulphuric acid (H₂SO₄) to each slowly. The one in which brown ring appears is sodium nitrate solution while the other is sodium chloride sol. 3. Add NaOH solution to both the solutions. The one which give a reddish brown ppt. is Iron(II) chloride solution and the one which gives blue ppt. is copper chloride solution.

13.

Give one test each to distinguish between the following pairs of chemicals solutions 1. Zn(NO3)2 and Ca(NO3)2 2. NaNO3 and NaCI 3. Iron [III] chloride and copper chloride.

Answer»

1. Add NaOH solution in excess to the two solutions. The one in which white ppt. initially formed dissolves in excess of NaOH solution is Zn(NO₃)₂ solution and the other is Ca(NO₃)₂ solution.

2. Add freshly prepared ferrous sulphate solution to the two solutions. Then by the side of the test tube, pour cone, sulphuric acid (H₂SO₄) to each slowly. The one in which brown ring appears is sodium nitrate solution while the other is sodium chloride sol.

3. Add NaOH solution to both the solutions. The one which give a reddish brown ppt. is Iron(II) chloride solution and the one which gives blue ppt. is copper chloride solution.

Discussion

14.	Identify the salts P and Q from the observations given below : 1. On performing the flame test salt P produces a lilac coloured flame and its solution gives a white precipitate with silver nitrate solution, which is soluble in ammonium hydroxide solution. 2. When dilute HCl is added to a salt Q, a brisk effervescence is produced and the gas turns lime water milky. When NH4OH solution is added to the above mixture [after adding dilute HCl], it produces a white precipitate which is soluble in excess NH4OH solution.
Answer» (i) The salt P is potassium chloride Reason : K⁺ ions give lilac colour to flame and Cl^– ions react with silver nitrate to form silver chloride precipitate which is soluble in excess of ammonium hydroxide. (ii) The salt Q is zinc carbonate Reason : CO₃ ^-2 ions are responsible for the liberation of carbon dioxide with HCl. The salt formed is zinc chloride which forms white precipitate with ammonium hydroxide. This precipitate is soluble in excess of ammonium hydroxide.

14.

Identify the salts P and Q from the observations given below : 1. On performing the flame test salt P produces a lilac coloured flame and its solution gives a white precipitate with silver nitrate solution, which is soluble in ammonium hydroxide solution. 2. When dilute HCl is added to a salt Q, a brisk effervescence is produced and the gas turns lime water milky. When NH4OH solution is added to the above mixture [after adding dilute HCl], it produces a white precipitate which is soluble in excess NH4OH solution.

Answer»

(i) The salt P is potassium chloride

Reason : K⁺ ions give lilac colour to flame and Cl^– ions react with silver nitrate to form silver chloride precipitate which is soluble in excess of ammonium hydroxide.

(ii) The salt Q is zinc carbonate

Reason : CO₃ ^-2 ions are responsible for the liberation of carbon dioxide with HCl. The salt formed is zinc chloride which forms white precipitate with ammonium hydroxide. This precipitate is soluble in excess of ammonium hydroxide.

Discussion

15.	State one chemical test between each of the Ferrous nitrate and Lead nitrate.
Answer» To each of the aqueous solutions of compounds add aqueous sodium hydroxide solution. A dirty green precipitate is formed in case of ferrous nitrate, whereas a white chalky precipitate is formed in case of lead nitrate

Discussion

16.	State one chemical test between each of the Manganese dioxide and Copper(II) oxide.
Answer» Heat each of the compound with cone, hydrochloric acid. In case of manganese dioxide a greenish yellow gas (chlorine) is evolved. In case of copper(II) oxide, no gas evolved and a bluish green solution is formed.

Discussion

17.	Identity the substances ‘R’ based on the information given below : The pale green solid ‘R’ turns reddish brown on heating. Its aqueous solution gives a white precipitate with barium chloride solution. The precipitate is insoluble in mineral acids.
Answer» Ferrous sulphate (Fe₂SO₄ ).

Discussion

18.	Carbon dioxide and sulphur dioxide gas can be distinguished by using : (A) Moist blue litmus paper (B) Lime water (C) Acidified potassium dichromate paper (D) None of the above.
Answer» The sulphur dioxide gas can be distinguished Acidified potassium dichromate paper.

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Give a chemical test to distinguish between the Lead chloride and lead sulphide.

Select the gas that has a charateristic rotten egg smell. [ammonia, ethane, hydrogen chloride, hydrogen sulphide, ethyne].

State your observation : When moist starch iodide paper is introduced into chlorine gas.

Gas Q turns moist lead acetate paper silvery black. Identify the gas Q. pH of liquid R is 10. What kind of substance is R?

State one relevant observation : When hydrogen sulphide gas is passed through lead acetate solution.

State your observation – 1. A piece of moist blue litmus paper 2. Paper soaked in potassium permanganate solution- is introduced into a gas jar of sulphur dioxide.

How will the addition of barium chloride soln. help to distinguish between dil. HCl and dil. H2SO4 .

From the list of substances given—Ammonium sulphate, Lead carbonate, Chlorine, Copper nitrate, Ferrous sulphate — State : A substance that turns moist starch iodide paper blue.

Write the equation for the reaction of magnesium sulphate solution with barium chloride solution.

Choose from the list of substances – Acetylence gas, aqua fortis, coke, brass, barium chloride, bronze, platinum. An aqueous salt solution used for testing sulphate radical.

Give a reason why carbon dioxide and sulphur dioxide cannot be distinguished by using lime water.

Give one test each to distinguish between the following pairs of chemicals solutions 1. Zn(NO3)2 and Ca(NO3)2 2. NaNO3 and NaCI 3. Iron [III] chloride and copper chloride.

State one chemical test between each of the Ferrous nitrate and Lead nitrate.

State one chemical test between each of the Manganese dioxide and Copper(II) oxide.

Identity the substances ‘R’ based on the information given below : The pale green solid ‘R’ turns reddish brown on heating. Its aqueous solution gives a white precipitate with barium chloride solution. The precipitate is insoluble in mineral acids.

Carbon dioxide and sulphur dioxide gas can be distinguished by using : (A) Moist blue litmus paper (B) Lime water (C) Acidified potassium dichromate paper (D) None of the above.