Study of Compounds: Ammonia — ICSE Class 10 Chemistry Important Questions
13 hand-picked ICSE Class 10 Chemistry important questions for Study of Compounds: Ammonia, each with a full model answer — the formats and topics most likely to appear in your board exam.
- 13
- Questions
- 6
- Question types
- 32
- Total marks
- ₹0
- With answers
High-yield ICSE Ammonia questions cover the Haber process (N_2+3H_2 2NH_3, iron catalyst, 200 atm, 450-500^ C), laboratory preparation from ammonium salts, the fountain experiment showing high solubility, ammonia as a base forming ammonium salts, its reducing and complex-forming nature, and the ring test with HCl. Uses in fertilisers and nitric acid manufacture are frequently asked.
About Study of Compounds: Ammonia
In the ICSE Class 10 Chemistry chapter Study of Compounds: Ammonia you study the industrial Haber process, the laboratory preparation of ammonia, its physical properties (very high solubility shown by the fountain experiment), its chemical behaviour as a base and a reducing agent, its reaction with hydrogen chloride (dense white fumes) and copper(II) ions, and its major industrial uses.
Key concepts & formulas
N_2(g)+3H_2(g) 2NH_3(g); conditions: pressure 200 atm, temperature 450-500^ C, finely divided iron catalyst with molybdenum promoter. The reaction is reversible and exothermic.
NH_3 dissolves in water: NH_3+H_2O→ NH_4OH, giving OH^- ions and turning red litmus blue. It neutralises acids to form ammonium salts, e.g. NH_3+HCl→ NH_4Cl.
Ammonia reduces heated metal oxides: 3CuO+2NH_3→ 3Cu+3H_2O+N_2. Black copper(II) oxide turns to reddish-brown copper.
Ammonia gas turns moist red litmus blue and gives dense white fumes of NH_4Cl with a glass rod dipped in concentrated HCl.
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Important questions with answers
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| Question type | Count | Marks |
|---|---|---|
| MCQ | 4 | 1 |
| Assertion–Reason | 1 | 1 |
| Very Short | 2 | 2 |
| Short Answer | 3 | 3 |
| Long Answer | 2 | 5 |
| Case-based | 1 | 4 |
Multiple-choice questions (1 mark)
The catalyst used in the Haber process for the manufacture of ammonia is:
- (a)
Platinum
- (b)
Finely divided iron
- (c)
Manganese dioxide
- (d)
Nickel
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Answer: (b) Finely divided iron.
Finely divided iron acts as the catalyst (with molybdenum as promoter) in N_2+3H_2 2NH_3.
The drying agent used to dry ammonia gas is:
- (a)
Concentrated H_2SO_4
- (b)
Anhydrous CaCl_2
- (c)
Quicklime (CaO)
- (d)
Phosphorus pentoxide (P_2O_5)
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Answer: (c) Quicklime (CaO).
Ammonia is basic, so acidic drying agents (H_2SO_4, P_2O_5) and CaCl_2 (forms CaCl_2·8NH_3) cannot be used. Only quicklime dries it.
When ammonia is passed over heated copper(II) oxide, the observation is:
- (a)
Black solid turns reddish-brown
- (b)
Reddish-brown solid turns black
- (c)
A blue solution is formed
- (d)
White fumes are evolved
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Answer: (a) Black solid turns reddish-brown.
3CuO+2NH_3→ 3Cu+3H_2O+N_2. Black CuO is reduced to reddish-brown copper, showing ammonia is a reducing agent.
The addition of excess ammonium hydroxide to a copper(II) sulphate solution finally gives:
- (a)
A pale blue precipitate that dissolves to a deep blue solution
- (b)
A white precipitate
- (c)
A dirty green precipitate
- (d)
No visible change
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Answer: (a) A pale blue precipitate that dissolves to a deep blue solution.
First CuSO_4+2NH_4OH→ Cu(OH)_2+(NH_4)_2SO_4 (pale blue ppt); with excess it dissolves forming the deep blue complex [Cu(NH_3)_4]^2+.
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Practise free with the AI tutor →Assertion–Reason questions (1 mark)
Assertion (A): Ammonia is collected by the downward displacement of air.
Reason (R): Ammonia is lighter than air and highly soluble in water.
- (a)
Both A and R are true and R is the correct explanation of A
- (b)
Both A and R are true but R is not the correct explanation of A
- (c)
A is true but R is false
- (d)
A is false but R is true
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Answer: (a) Ammonia is lighter than air (so collected by downward displacement of air, i.e. an inverted jar) and is highly soluble (so cannot be collected over water); R correctly explains A.
Very short answer questions (2 marks)
Write the balanced equation for the laboratory preparation of ammonia from ammonium chloride and slaked lime, and name the drying agent used.
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2NH_4Cl+Ca(OH)_2→ (Δ)CaCl_2+2NH_3+2H_2O
The gas is dried by passing it over quicklime (calcium oxide, CaO).
State what is observed when a glass rod dipped in concentrated hydrochloric acid is brought near a jar of ammonia. Give the equation.
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Dense white fumes of ammonium chloride are formed.
NH_3+HCl→ NH_4Cl
This is the standard test used to identify ammonia gas.
Short answer questions (3 marks)
Describe the fountain experiment. What does it demonstrate, and why is the fountain coloured red (or pink)?
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A dry round-bottomed flask is filled with dry ammonia and fitted with a stopper carrying a jet tube and a dropper containing water. A small amount of water is squeezed in from the dropper.
Observation: Ammonia dissolves rapidly, creating a partial vacuum, so water rushes up the jet tube and gushes out as a fountain inside the flask.
It demonstrates that ammonia is extremely soluble in water. If red litmus (or phenolphthalein) is added to the water, the fountain appears blue (or pink) because the ammonia solution (NH_4OH) is alkaline.
State the optimum conditions of temperature, pressure and catalyst for the Haber process and explain why a moderate temperature of about 450^ C is used rather than a very low temperature.
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Conditions: pressure 200 atm; temperature 450-500^ C; catalyst finely divided iron with molybdenum as promoter.
N_2(g)+3H_2(g) 2NH_3(g) (exothermic).
Since the forward reaction is exothermic, a low temperature would favour a higher yield of ammonia, but at low temperature the reaction becomes very slow. A moderate temperature of about 450^ C is therefore chosen as a compromise: it gives a reasonable yield of ammonia at an acceptably fast rate.
Ammonia acts as a reducing agent. Illustrate this with (i) its reaction with heated copper(II) oxide and (ii) its reaction with chlorine (excess chlorine). Give balanced equations.
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(i) With heated copper(II) oxide:
3CuO+2NH_3→ 3Cu+3H_2O+N_2
Black CuO is reduced to reddish-brown copper; ammonia is oxidised to nitrogen, so it acts as a reducing agent.
(ii) With excess chlorine:
8NH_3+3Cl_2→ 6NH_4Cl+N_2
Ammonia reduces chlorine; the nitrogen of ammonia is oxidised to N_2 while Cl_2 is reduced to chloride. (With excess ammonia the products are N_2 and NH_4Cl; note that with excess chlorine the explosive NCl_3 can form.)
Long answer questions (5 marks)
With a labelled diagram, describe the laboratory preparation of ammonia gas. Include the reactants, equation, method of collection, drying agent, and why concentrated sulphuric acid and calcium chloride are unsuitable drying agents.
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Reactants: an ammonium salt (ammonium chloride) heated with slaked lime.
2NH_4Cl+Ca(OH)_2→ (Δ)CaCl_2+2NH_3+2H_2O
Collection: Ammonia is lighter than air and very soluble in water, so it is collected by the downward displacement of air in an inverted gas jar (not over water).
Drying agent: the gas is dried by passing it over quicklime (CaO).
Unsuitable agents:
- Concentrated H_2SO_4 and P_2O_5 are acidic, so they react with basic ammonia: 2NH_3+H_2SO_4→(NH_4)_2SO_4.
- Anhydrous CaCl_2 cannot be used because it forms the compound CaCl_2·8NH_3.
(a) State three important uses of ammonia. (b) Ammonia solution is added drop by drop, and then in excess, to solutions of (i) iron(III) chloride and (ii) zinc sulphate. State the observations and give equations.
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(a) Uses of ammonia:
- Manufacture of nitric acid by the Ostwald process.
- Manufacture of nitrogenous fertilisers such as urea and ammonium sulphate.
- As a refrigerant in ice plants and in the manufacture of washing soda (Solvay process); also in cleaning agents.
(b)(i) Iron(III) chloride: a reddish-brown precipitate of iron(III) hydroxide forms and is insoluble in excess.
FeCl_3+3NH_4OH→ Fe(OH)_3+3NH_4Cl
(b)(ii) Zinc sulphate: a white gelatinous precipitate of zinc hydroxide forms, which dissolves in excess ammonium hydroxide to give a colourless solution of the complex.
ZnSO_4+2NH_4OH→ Zn(OH)_2+(NH_4)_2SO_4
Zn(OH)_2+4NH_4OH→[Zn(NH_3)_4](OH)_2+4H_2O
Case-based questions (4 marks)
A student prepares ammonia in the laboratory and studies its properties. Answer the following:
(i) Name the gas evolved and the colour change it produces on moist red litmus paper.
(ii) The student burns ammonia in an atmosphere of oxygen. Write the equation for ordinary combustion.
(iii) In presence of a heated platinum catalyst, ammonia is catalytically oxidised. Write this equation and name the process it begins.
(iv) Why is ammonia not collected over water?
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(i) Ammonia (NH_3); it turns moist red litmus blue (it is alkaline).
(ii) Ordinary combustion in oxygen:
4NH_3+3O_2→ 2N_2+6H_2O
(iii) Catalytic oxidation over heated platinum:
4NH_3+5O_2→ (Pt, 800^ C)4NO+6H_2O
This is the first step of the Ostwald process for manufacturing nitric acid.
(iv) Ammonia is highly soluble in water, so it would dissolve and could not be collected over water.
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Yes — they are aligned to the CISCE latest syllabus syllabus for ICSE Class 10 Chemistry, so nothing here is outside the current course.How should I practise the Study of Compounds: Ammonia important questions?
Attempt each question on paper first, then reveal the model answer to check your method — not just the final result. Re-do anything you got wrong the same day.What types of questions are covered for Study of Compounds: Ammonia?
A full mix — multiple-choice questions, assertion–reason questions, very short answer questions, short answer questions, long answer questions, case-based questions — so every format in the ICSE paper is covered.
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