Class 10 Analytical Chemistry Mock Test (ICSE)

Topics in Analytical Chemistry

• Action of sodium hydroxide on salt solutions
• Action of ammonium hydroxide on salt solutions
• Identification of cations by precipitate colour
• Amphoteric oxides and hydroxides

Analytical Chemistry practice questions with answers

1. Q1Multiple choice·1 mark
   Lead(II) hydroxide dissolves in excess sodium hydroxide solution to form:

   1. (a)Lead(II) oxide and hydrogen
   2. (b)Sodium plumbite and water
   3. (c)Sodium plumbite and hydrogen
   4. (d)Sodium plumbate and water
   Show answer and step marks

   1. Correct option: (b) Sodium plumbite and water+1

   Answer: (b)
2. Q2Multiple choice·1 mark
   When an excess of ammonium hydroxide is added to a lead(II) salt solution, the correct observation is:

   1. (a)A gelatinous white precipitate is formed which is soluble in excess.
   2. (b)A reddish-brown precipitate is formed which is insoluble in excess.
   3. (c)A chalky white precipitate is formed which is insoluble in excess.
   4. (d)A chalky white precipitate is formed which is soluble in excess.
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   1. Correct option: (c) A chalky white precipitate is formed which is insoluble in excess.+1

   Answer: (c)
3. Q3Multiple choice·1 mark
   Which of the following cations forms a dirty green precipitate with sodium hydroxide solution, which is insoluble in excess?

   1. (a)$\text{Fe}^{3+}$
   2. (b)$\text{Zn}^{2+}$
   3. (c)$\text{Fe}^{2+}$
   4. (d)$\text{Cu}^{2+}$
   Show answer and step marks

   1. Correct option: (c) $\text{Fe}^{2+}$+1

   Answer: (c)
4. Q4Multiple choice·1 mark
   When sodium hydroxide solution is added dropwise to an iron(III) salt solution, the resulting observation is:

   1. (a)A reddish-brown precipitate insoluble in excess
   2. (b)A dirty green precipitate insoluble in excess
   3. (c)A gelatinous white precipitate soluble in excess
   4. (d)A pale blue precipitate soluble in excess
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   1. Correct option: (a) A reddish-brown precipitate insoluble in excess+1

   Answer: (a)
5. Q5Long answer·4 marks
   (a) Name the cation which gives a chalky white precipitate with sodium hydroxide solution, where the precipitate is insoluble in excess of the reagent. (b) State the observation when ammonium hydroxide is added dropwise, followed by in excess, to a solution of iron(II) sulphate. (c) Write balanced chemical equations for the following: (i) Action of excess sodium hydroxide solution on zinc sulphate solution. (ii) Action of ammonium hydroxide solution on copper(II) sulphate solution till excess is added.
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   1. (a) Calcium ion ($\text{Ca}^{2+}$)+1
   2. (b) A dirty green precipitate is formed which is insoluble in excess of ammonium hydroxide.+1
   3. (c)(i) $\text{ZnSO}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + \text{Zn(OH)}_2\downarrow$ $\text{Zn(OH)}_2 + 2\text{NaOH (excess)} \rightarrow \text{Na}_2\text{ZnO}_2 + 2\text{H}_2\text{O}$+1
   4. (c)(ii) $\text{CuSO}_4 + 2\text{NH}_4\text{OH} \rightarrow \text{Cu(OH)}_2\downarrow \text{ (pale blue ppt)} + (\text{NH}_4)_2\text{SO}_4$ $\text{Cu(OH)}_2 + (\text{NH}_4)_2\text{SO}_4 + 2\text{NH}_4\text{OH (excess)} \rightarrow [\text{Cu(NH}_3)_4]\text{SO}_4 \text{ (ink-blue solution)} + 4\text{H}_2\text{O}$+1

   Answer: (a) Calcium ion ($\text{Ca}^{2+}$). (b) A dirty green precipitate forms, insoluble in excess ammonium hydroxide. (c)(i) $\text{ZnSO}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + \text{Zn(OH)}_2\downarrow$, then $\text{Zn(OH)}_2 + 2\text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + 2\text{H}_2\text{O}$. (ii) $\text{CuSO}_4 + 2\text{NH}_4\text{OH} \rightarrow \text{Cu(OH)}_2\downarrow + (\text{NH}_4)_2\text{SO}_4$, then $\text{Cu(OH)}_2 + (\text{NH}_4)_2\text{SO}_4 + 2\text{NH}_4\text{OH} \rightarrow [\text{Cu(NH}_3)_4]\text{SO}_4 + 4\text{H}_2\text{O}$ (ink-blue solution).

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