Class 10 Study of Compounds: Ammonia Mock Test (ICSE)

Topics in Study of Compounds: Ammonia

• Laboratory preparation of ammonia
• Haber's process
• Properties of ammonia
• Catalytic oxidation of ammonia
• Uses of ammonia

Study of Compounds: Ammonia practice questions with answers

1. Q1Multiple choice·1 mark
   Liquid ammonia is commonly used in ice plants and refrigerators because:

   1. (a)It has a high latent heat of vaporization
   2. (b)It reacts violently with water
   3. (c)It is a good solvent for ionic compounds
   4. (d)It turns moist red litmus blue
   Show answer and step marks

   1. Correct option: (a) It has a high latent heat of vaporization+1

   Answer: (a)
2. Q2Multiple choice·1 mark
   During the catalytic oxidation of ammonia, once the reaction is initiated, the external heating is removed because:

   1. (a)The reaction is exothermic and the heat evolved keeps the platinum catalyst glowing red-hot
   2. (b)The reaction is highly endothermic and absorbs surrounding heat
   3. (c)The reaction stops producing nitric oxide if heating is continued
   4. (d)The catalyst melts at high temperatures and requires cooling
   Show answer and step marks

   1. Correct option: (a) The reaction is exothermic and the heat evolved keeps the platinum catalyst glowing red-hot+1

   Answer: (a)
3. Q3Multiple choice·1 mark
   In the laboratory preparation of ammonia gas, the drying agent used is:

   1. (a)Phosphorus pentoxide
   2. (b)Concentrated sulphuric acid
   3. (c)Anhydrous calcium chloride
   4. (d)Quicklime
   Show answer and step marks

   1. Correct option: (d) Quicklime+1

   Answer: (d)
4. Q4Multiple choice·1 mark
   Which of the following conditions favors the maximum yield of ammonia in Haber's process?

   1. (a)High temperature and high pressure
   2. (b)Low temperature and high pressure
   3. (c)High temperature and low pressure
   4. (d)Low temperature and low pressure
   Show answer and step marks

   1. Correct option: (b) Low temperature and high pressure+1

   Answer: (b)
5. Q5Long answer·4 marks
   During the manufacture of nitric acid by Ostwald's process, ammonia undergoes catalytic oxidation. (a) Write the balanced chemical equation for the catalytic oxidation of ammonia, specifying the catalyst and the optimum temperature required. (b) State the observation when the colorless gas formed in this reaction is exposed to air.
   Show answer and step marks

   1. (a) Balanced equation: $4\text{NH}_3\text{(g)} + 5\text{O}_2\text{(g)} \rightarrow 4\text{NO}\text{(g)} + 6\text{H}_2\text{O}\text{(g)} + \text{Heat}$+1.5
   2. (a) Catalyst: platinum (platinum gauze).+0.5
   3. (a) Optimum temperature: about $800^\circ\text{C}$.+0.5
   4. (b) Observation: the colourless gas turns reddish-brown in air (reddish-brown fumes appear).+1.5

   Answer: (a) $4\text{NH}_3 + 5\text{O}_2 \rightarrow 4\text{NO} + 6\text{H}_2\text{O} + \text{Heat}$, with a platinum catalyst at about $800^\circ\text{C}$. (b) The colourless gas (nitric oxide) turns reddish-brown in air, as nitrogen dioxide forms.
6. Q6Long answer·4 marks
   (a) Name the catalyst and the optimum temperature required for the catalytic oxidation of ammonia. Write the balanced chemical equation for the process. (b) State the observation when the nitric oxide gas formed in the above reaction comes in contact with air, and write the balanced equation for it. (c) Name the acid produced when the gas obtained in part (b) is dissolved in water in the presence of excess oxygen.
   Show answer and step marks

   1. (a) Catalyst: platinum (platinum gauze, $\text{Pt}$).+0.5
   2. (a) Optimum temperature: about $800^\circ\text{C}$.+0.5
   3. (a) Balanced equation: $4\text{NH}_3 + 5\text{O}_2 \xrightarrow[\text{Pt}]{800^\circ\text{C}} 4\text{NO} + 6\text{H}_2\text{O}$+1
   4. (b) Observation: the colourless nitric oxide turns into reddish-brown fumes of nitrogen dioxide in air.+0.5
   5. (b) Balanced equation: $2\text{NO} + \text{O}_2 \rightarrow 2\text{NO}_2$+1
   6. (c) The acid formed is nitric acid ($\text{HNO}_3$): $4\text{NO}_2 + 2\text{H}_2\text{O} + \text{O}_2 \rightarrow 4\text{HNO}_3$.+0.5

   Answer: (a) Catalyst: platinum; temperature: about $800^\circ\text{C}$; $4\text{NH}_3 + 5\text{O}_2 \xrightarrow{\text{Pt}} 4\text{NO} + 6\text{H}_2\text{O}$. (b) Reddish-brown fumes of $\text{NO}_2$ form; $2\text{NO} + \text{O}_2 \rightarrow 2\text{NO}_2$. (c) Nitric acid ($\text{HNO}_3$).

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