CBSE Class 10 Science Acids Bases and Salts Assignment Set 05

Question. Which of the methods, A, B, C, D or E is generally used for preparing the chlorides listed below from (i) to (v)
(a) Action of an acid on a metal
(b) Action of an acid on an oxide or carbonate
(c) Direct combination
(d) Neutralization of an alkali by an acid
(e) Precipitation (double decomposition)
1. Copper (II) chloride
2. Iron (II) chloride
3. Iron (III) chloride
4. Lead (II) chloride
5. Sodium chloride Each method is to be used only once.
Answer: (1) B, (2) A, (3) C, (4) E, (5) D

Question. Match from A to F:
A: Acidic oxide,
B: Alkali,
C: Amphoteric oxide,
D: Basic oxide,
E: Deliquescence,
F: Efflorescence
1. The property of spontaneously giving up water of crystallization to the atmosphere.
2. A compound, soluble in water and the only negative ions in the soln. are hydroxide ions
Answer:
1. F: Efflorescence
2. B: Alkali

Question. What is observed when, neutral litmus soln. is added to sodium hydrogen carbonate solution.
Answer:
\( \text{NaHCO}_3 + \text{H}_2\text{O} \rightarrow \text{NaOH [strong alkali]} + \text{H}_2\text{CO}_3 \text{ [weak acid]} \)
Alkaline Purple to — Blue

The preparation of lead sulphate from lead carbonate is a two-step process. (Lead sulphate cannot be prepared by adding dilute sulphuric from lead carbonate.)

Question. What is the first step that is required to prepare lead sulphate from lead carbonate.
Answer: Treatment with dil. nitric acid to form soluble lead nitrate.

Question. Write the equation for the reaction that will take place when this first step is carried out.
Answer: \( \text{PbCO}_3\text{ (Insoluble)} + 2\text{HNO}_3 \rightarrow \text{Pb(NO}_3)_2 + \text{H}_2\text{O} + \text{CO}_2\uparrow \)

Question. Why is the direct addition of dil. \( \text{H}_2\text{SO}_4 \) to \( \text{PbCO}_3 \) an impractical method of preparing lead sulphate.
Answer: Direct addition of dil. sulphuric acid to lead carbonate will lead to deposition of lead sulphate on the surface of lead carbonate which stops further reaction of sulphuric acid on it.

Question. Fill in the blanks:
An acid is a compound which when dissolved in water forms hydronium ions as the only (1) …. ions. A base is a compound which if soluble in water contains (2)…. ions. A base reacts with an acid to form a (3)…… and water only. This type of reaction is known as (4)…….
Answer:
1. Positive
2. Hydroxyl
3. Salt
4. neutralization.

Question. Acid dissolve in water to produce positively charged ions. Draw the structure of these ions
Answer:
The hydronium ion (\( \text{H}_3\text{O}^+ \)) structural formula showing sharing of electrons:
\( \left[ \text{H} - \underset{\underset{\text{H}}{|}}{\ddot{\text{O}}} - \text{H} \right]^+ \)

Question. Name the ion other than ammonium ion formed when ammonia dissolves in water. Give one test that can be used to detect the presence of the ion product.
Answer: Hydroxide ion.

Question. Mention the colour changes observed when the following indicators are added to acids:
1. Alkaline phenolphthalein solution.
2. Methyl orange solution
3. Neutral litmus solution
Answer:
1. Pink solution becomes colourless
2. Orange solution changes to red or pink
3. It turns red

Question. Which of the following hydroxides is not an alkali
(a) ammonium hydroxide
(b) calcium hydroxide
(c) copper hydroxide
(d) sodium hydroxide
Answer: (c) copper hydroxide

Question. Complete the blanks from the list given:
Ammonia, Ammonium, Carbonate, Carbon dioxide, Hydrogen, Hydronium, Hydroxide, Precipitate, Salt, Water. A solution X turns blue litmus red, so it must contain (1) …. ions ; another solution Y turns red litmus blue and therefore, must contain (2)……. ions. When solutions X and Y are mixed together the products will be a (3) …. and (4) If a piece of magnesium were put into solution X, (5)….. gas would be evolved.
Answer:
1. hydronium
2. hydroxide
3. salt
4. water
5. hydrogen

Question. Match the following:
Column A — Column B
1. Acid salt — A. Sodium potassium carbonate
2. Normal salt — B. Alum
3. Complex salt — C. Sodium carbonate
4. Double salt — D. Sodium zincate
5. Mixed salt — E. Sodium hydrogencarbonate
Answer:
1. Acid salt — E. Sodium hydrogen bicarbonate
2. Normal salt — C. Sodium carbonate
3. Complex salt — D. Sodium zincate
4. Double salt — B. Alum
5. Mixed salt — A. Sodium potassium carbonate

Question. Write balanced equation for formation of \( \text{PbCl}_2 \) from \( \text{Pb(NO}_3)_2 \) soln. and \( \text{NaCl} \) soln.
Answer: \( \text{Pb(NO}_3)_2 + 2\text{NaCl} \rightarrow \text{PbCl}_2 + 2\text{NaNO}_3 \)

Question. What is the term defined i) A base which is soluble in water.
Answer: Alkali.

Question. The acid which contains four hydrogen atoms —
(a) Formic acid
(b) Sulphuric acid
(c) Nitric acid
(d) Acetic acid
Answer: (d) Acetic acid

Question. A black coloured solid which on reaction with dilute sulphuric acid forms a blue coloured solution is:
(a) Carbon
(b) Managanese (IV) oxide
(c) Lead (II) oxide
(d) Copper (II) oxide
Answer: (d) Copper (II) oxide

Solution A is a strong acid
Solution B is a weak acid
Solution C is a strong alkali

Question. Which solution contains solute molecules in addition to water molecules ?
Answer: Solution B — weak acid

Question. Which solution will give a gelatinous white precipitate with zinc sulphate solution?
The precipitate disappears when an excess of the solution is added.
Answer: Solution C — strong alkali

Question. Which solution could be a solution of glacial acetic acid ?
Answer: Solution B — weak acid

Question. Give an example of a solution which is a weak alkali.
Answer: Ammonium hydroxide — weak alkali

Question. Write the equation(s) for the reaction(s) to prepare lead sulphate from lead carbonate.
Answer:
\( \text{PbCO}_3 + 2\text{HNO}_3 \rightarrow \text{Pb(NO}_3)_2 + \text{H}_2\text{O} + \text{CO}_2 \)
(Lead carbonate + Nitric acid \(\rightarrow\) Lead nitrate + water + carbon dioxide)

\( \text{Pb(NO}_3)_2 + \text{H}_2\text{SO}_4 \rightarrow \text{PbSO}_4 + 2\text{HNO}_3 \)
(Lead nitrate + sulphuric acid \(\rightarrow\) Lead sulphate + Nitric acid)

Question. Define the following terms : Neutralization
Answer: Neutralisation: The reaction in which an acid reacts with a base to form salt and water is known as neutralisation.
Example : \( \text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O} \)
(base + acid \(\rightarrow\) salt + water)

Question. A: Nitroso Iron (II) sulphate
B: Iron (III) chloride
C: Chromium sulphate
D: Lead (II) chloride
E: Sodium chloride.
Select from A, B, C, D and E —
1. A compound soluble in hot water but insoluble in cold water.
2. A compound which in the aqueous solution state,is neutral in nature.
3. A deliquescent compound.
Answer:
1. Lead (II) chloride
2. Sodium chloride
3. Iron (II) chloride

Question. A weak organic acid is:
(a) Formic acid
(b) Sulphuric acid
(c) Nitric acid
(d) Hydrochloric acid
Answer: (a) Formic acid

Question. A complex salt is:
(a) Zinc sulphate
(b) Sodium hydrogen sulphate
(c) Iron (II) ammonium sulphate
(d) Tetrammine copper (II) sulphate
Answer: (d) Tetrammine copper (II) sulphate

Question. Give an equation for the conversions
1. \( \text{ZnSO}_4 \) to \( \text{ZnCO}_3 \)
2. \( \text{ZnCO}_3 \) to \( \text{Zn(NO}_3)_2 \)
Answer:
(1) \( \text{ZnSO}_4 + \text{Na}_2\text{CO}_3 \rightarrow \text{ZnCO}_3 + \text{Na}_2\text{SO}_4 \)
(zinc sulphate + sodium carbonate \(\rightarrow\) zinc carbonate + sodium sulphate)

(2) \( \text{ZnCO}_3 + 2\text{HNO}_3 \rightarrow \text{Zn(NO}_3)_2 + \text{H}_2\text{O} + \text{CO}_2\uparrow \)
(zinc carbonate + nitric acid \(\rightarrow\) zinc nitrate + water + carbon dioxide)

Question. A: NaOH sol. : B: weak acid C: Dil. H2SO4
Select the one which contains solute ions and molecules.
Answer:
1. Solution C
2. Solution A
3. Solution B

Question. Give balanced equation/s for the preparation of the following salts:
1. Copper (II) sulphate from CuO.
2. Iron (III) chloride from Fe.
3. \( \text{K}_2\text{SO}_4 \) from KOH sol.
4. Lead (II) chloride from \( \text{PbCO}_3 \) (give two equations)
Answer:
(1) \( \text{CuO} + \text{H}_2\text{SO}_4 \rightarrow \text{CuSO}_4 + \text{H}_2\text{O} \)
(Copper (II) oxide + Sulphuric acid \(\rightarrow\) Copper sulphate + Water)

(2) \( 2\text{Fe} + 3\text{Cl}_2 \rightarrow 2\text{FeCl}_3 \)
(Iron + Chlorine \(\rightarrow\) Ferric chloride)

(3) \( 2\text{KOH} + \text{H}_2\text{SO}_4 \xrightarrow{\text{Temp. above } 200^{\circ}\text{C}} \text{K}_2\text{SO}_4 + 2\text{H}_2\text{O} \)
(Potassium hydroxide + Sulphuric acid \(\rightarrow\) Potassium sulphate + Water)

(4) • \( \text{PbCO}_3\text{ (Insoluble salt)} + 2\text{HNO}_3 \rightarrow \text{Pb(NO}_3)_2\text{ (Soluble salt)} + \text{H}_2\text{O} + \text{CO}_2 \)
• \( \text{Pb(NO}_3)_2 + 2\text{HCl} \rightarrow \text{PbCl}_2 + 2\text{HNO}_3 \)
(Lead nitrate + Hydrochloric acid \(\rightarrow\) Lead chloride + Nitric acid)

Question. Write the balanced chemical equation: Lead nitrate solution is added to sodium chloride solution
Answer: \( \text{Pb(NO}_3)_2 + 2\text{NaCl} \rightarrow \text{PbCl}_2 + 2\text{NaNO}_3 \)

Question. Name the method used from the list:
A: Simple displacement
B: Neutralization
C: Decomposition by acid
D: Double decomposition
E: Direct synthesis
For preparation of the following salts –
1. Sodium nitrate
2. Iron (III) chloride
3. Lead chloride
4. Zinc sulphate
5. Sodium hydrogen sulphate.
Answer:
(1) Sodium nitrate (B) Neutralisation
(2) Iron (III) chloride (E) Direct synthesis
(3) Lead chloride (D) Double decomposition
(4) Zinc sulphate (A) Simple displacement
(5) Sodium hydrogen sulphate (C) Decomposition by acid

Question. Match the following:
Column A
1. Acid salt A.
2. Double salt
3. Ammonium hydroxide
4. Dilute hydrochloric acid
5. Carbon tetrachloride
Column B
A. Ferrous ammonium sulphate
B. Contains only ions
C. Sodium hydrogen sulphate solution
D. Contains only molecules
E. Contains ions and molecules
Answer:
Column A — Column B
1. Acid salt — C. Sodium hydrogen sulphate solution
2. Double salt — A. Ferrous ammonium sulphate
3. Ammonium hydroxide — E. Contains ions and molecules
4. Dilute hydrochloric acid — B. Contains only ions
5. Carbon tetrachloride — D. Contains only molecules

Question. Select the words given below which are required to correctly complete the blanks –
[ammonia, ammonium, carbonate, carbon dioxide, hydrogen, hydronium, hydroxide, precipitate, salt water]:
1. A solultion M turns blue litmus red, so it must contain (1)………..ions ; another solution O turns red litmus blue and hence, must contain, (2)……… ions.
2. When solution M and O are mixed together, the products will be (3)………. and (4) ……………..
3. If a piece of magnesium was put into a solution M,(5)……………..gas would be evolved.
Answer: (1) hydronium (2) hydroxide (3) salt (4) water (5) hydrogen.

Question. Give a suitable chemical term for:
1. A salt formed by incomplete neutralisation of an acid by a base.
2. A definite number of water molecules bound to some salts.
Answer:
1. Acid salt
2. Water of crystallisation

Question. Choosing the substances from the list given:
dil. Sulphuric acid, Copper, Iron, Sodium, Copper (II) carbonate, Sodium carbonate, Sodium chloride, Zinc nitrate
Write balanced equations for the reactions which would be used in the laboratory to obtain the following salts:
1. Sodium sulphate
2. Zinc carbonate
3. Copper (II) sulphate
4. Iron (II) sulphate.
Answer:
1. Sodium sulphate
\( \text{Na}_2\text{CO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + \text{HzO} + \text{CO}_2 \)

2. Zinc carbonate
\( \text{Zn(NO}_3\text{)}_2 + \text{Na}_2\text{CO}_3 \rightarrow \text{ZnCO}_3 + 2\text{NaNO}_3 \)

3. Copper (II) sulphate
\( \text{CuCO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{CuSO}_4 + \text{h}_2\text{o} + \text{CO}_2 \)

4. Iron (II) sulphate.
\( \text{Fe} + \text{H}_2\text{SO}_4 \rightarrow \text{FeSO}_4 + \text{H}_2 \)

Question. Identify: An acid which is present in vinegar.
Answer: Acetic acid or ethanoic acid.

Question. Fill in the blank from the choices given:
The basicity of Acetic Acid is ______.
Answer: 1.

Question. Draw the structure of the stable positive ion formed when an acid dissolves in water.
Answer:
\( \text{HCl} + \text{H}_2\text{O} \rightarrow \text{H}_3\text{O}^+ + \text{Cl}^- \)

   ..
H--O--H
   |
   H

Question. State the inference drawn from the following observations:
Salt S is prepared by reacting dilute sulphuric acid with copper oxide. Identify S.
Answer:
The compound or salt S is copper sulphate \( \text{CuSO}_4 \)
\( \text{CuO} + \text{H}_2\text{SO}_4 \rightarrow \text{CuSO}_4 + \text{H}_2\text{O} \)

Question. Give balanced chemical equations to prepareation of the following salts:
1. Lead sulphate-from lead carbonate.
2. Sodium sulphate-using dilute sulphuric acid.
3. Copper chloride-using copper carbonate.
Answer:
(1) Lead sulphate from lead carbonate.
\( \text{PbCO}_3 + \text{HNO}_3 \rightarrow \text{Pb(NO}_3\text{)}_2 + \text{H}_2\text{O} + \text{CO}_2 \)
\( \text{Pb(NO}_3\text{)}_2 + \text{H}_2\text{SO}_4 \rightarrow \text{PbSO}_4 + 2\text{HNO}_3 \)

(2) Sodium sulphate using dilute sulphuric acid.
\( \text{Na}_2\text{CO}_3 + \text{H}_2\text{SO}_4\text{(dil)} \rightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{O} + \text{CO}_2 \)

(3) Copper chloride using copper carbonate.
\( \text{CuCO}_3 + \text{HCl(dil)} \rightarrow \text{CuCl}_2 + \text{H}_2\text{O} + \text{CO}_2 \)
(Insoluble)

Question. Give balanced chemical equations for the following conversions:
\( \text{Fe} \rightarrow \text{FeCl}_2 \), \( \text{Fe} \rightarrow \text{FeCl}_3 \)
Answer:
\( 2\text{Fe} + 3\text{Cl}_2 \xrightarrow{\text{Heat}} 2\text{FeCl}_3 \)

Question. From the list of salts — AgCl, MgCl2, NaHSO4, PbCO3, ZnCO3, KNO3, Ca(NO3)2 Choose the salt that most appropriately fits the description given below:
1. A deliquescent salt.
2. An insoluble chloride.
Answer:
1. A deliquescent salt = \( \text{MgCl}_2 \)
2. An insoluble chloride = \( \text{AgCl} \)

Question. From the following list of oxides — SO2, SiO2, Al2O3, MgO, CO, Na2O -Select an oxide which dissolves in water forming an acid.
Answer: \( \text{SO}_2 \)

Question. Fill in the blank:
Higher the pH value of a solution, the more………… (acidic / alkaline) it is.
Answer: Higher the pH value of a solution, the more alkaline it is.

Question. Match the following salts given below:
(1) Pb(NO3)2 from PbO
(2) MgCl2 from Mg
(3) FeCl3 from Fe
(4) NaNO3 from NaOH
(5) ZnCO3 from ZnSO4
With their correct method of preparation from: A, B, C, D and E.
(A) Simple displacement
(B) Titration
(C) Neutralization
(D) Precipitation
(E) Combination
Answer:
Column I — Column II
(1) \( \text{Pb(NO}_3\text{)}_2 \) from PbO — (C) Neutralization
(2) \( \text{MgCl}_2 \) from Mg — (A) Simple displacement
(3) \( \text{FeCl}_3 \) from Fe — (E) Combination
(4) \( \text{NaNO}_3 \) from NaOH — (B) Titration
(5) \( \text{ZnCO}_3 \) from \( \text{ZnSO}_4 \) — (D) Precipitation

Question. Fill in the blanks from the choices given in brackets –
When a metallic oxide is dissolved in water, the solution formed has a high concentration of________ ions. [H+,H3O+, OH ]
Answer: When a metallic oxide is dissolved in water, the solution formed has a high concentration of \( \text{OH}^- \) ions.

Question. Choose the correct answer from the options –
(1) to increase the pH value of a neutral solution, we should add:
(a) An acid
(b) An acid salt
(c) An alkali
(d) A salt
(2) Anhydrous iron [III] chloride is prepared by:
(A) direct combination;
(B) Simple displacement;
(C) Decomposition;
(D) Neutralization.
Answer: (c) An alkali

Question. Write a balanced chemical equation for the preparation of each of the following salts:
1. Copper carbonate,
2. Ammonium sulphate crystals.
Answer:
\( \text{CuSO}_4\text{(aq)} + \text{Na}_2\text{CO}_3\text{(uq)} \rightarrow \text{Na}_2\text{SO}_4\text{(aq)} + \text{CuCO}_3\text{(s)} \)
\( 2\text{NH}_4\text{OH(aq)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow \text{(NH}_4\text{)}_2\text{SO}_4 + 2\text{H}_2\text{O} \)

Additional Questions

Question. Define the following as per ionic theory with examples and ionic equations wherever relevant:
(1) acid
(2) base
(3) alkali
(4) neutralization
Answer:
(1) Acid — An acid is a compound which when dissolved in water yields – hydronium ions (\( \text{H}_3\text{O}^+ \)) as the only positively charged ion.
\( \text{HCl} + \text{H}_2\text{O} \rightleftharpoons \text{H}_3\text{O}^+ + \text{Cl}^- \)

(2) Base — A base is a compound which reacts with hydronium ions of an acid – to give salt and water
\( \text{CuO} + 2\text{HCl} \rightarrow \text{CuCl}_2 + \text{H}_2\text{O} \)

(3) Alkali — An alkali is a compound which when dissolved in water yields Hydroxyl ions (\( \text{OH}^- \)) as they are negatively charged ions. Alkali is a base soluble in water.
\( \text{NaOH (aq.)} \rightleftharpoons \text{Na}^+ + \text{OH}^- \)

(4) Neutralization — \( |\text{H}^+| \) ions of an acid completely or combine with \( |\text{OH}^-| \) ions of a base to give salt and water only.
Acid + Base \( \rightarrow \) Salt + Water
\( \text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2\text{O} \)

Question. Differentiate between:
1. Organic and inorganic acids
2. Hydracids and oxyacids with examples.
Answer:
(1) Organic acids – Those acids which are derived from plants, e.g., citric acid, acetic acid, tartaric acid.
Inorganic acids – Acids derived from minerals, e.g., \( \text{HCl} \), \( \text{H}_2\text{SO}_4 \).

(2) Hydracids – Acids containing hydrogen and a non-metallic element other than oxygen, e.g., \( \text{HCl} \), \( \text{HBr} \), \( \text{HI} \).
Oxyacids – Acids containing hydrogen, another element and oxygen, e.g., \( \text{HNO}_3 \), \( \text{H}_2\text{SO}_4 \).

Question. State on what basis does the strength of an acid and an alkali depend on.
Answer: Strength of acids depends upon concentration of hydronium ion \( |\text{H}_3\text{O}^+| \) present in an aqueous solution of an acid. Strength of alkali depends on the concentration of the hydroxyl ions \( |\text{OH}^-| \) present in an aqueous solution of an alkali.

Question. Differentiate between (1) strong and weak acid (2) strong and weak alkali with suitable examples and ionic equations.
Answer:
(1) Strong Acid – Is an acid which dissociates – almost completely in aqueous solution there by producing a – high concentration of hydrogen [\( \text{H}^+ \)] ions [or \( \text{H}_3\text{O}^+ \) ions].
Examples: Hydrochloric, Sulphuric and Nitric acid.
\( \text{HNO}_3 + \text{H}_2\text{O} \rightleftharpoons \text{H}_3\text{O}^+ + \text{NO}_3^- \)
\( \text{H}_2\text{SO}_4 + 2\text{H}_2\text{O} \rightleftharpoons 2\text{H}_3\text{O}^+ + \text{SO}_4^{2-} \)
[contains almost-only ions]

Weak Acid – Is an acid which dissociates – only partially in a aqueous solution thereby producing a – low concentration of hydrogen [\( \text{H}^+ \)] ions [or \( \text{H}_3\text{O}^+ \) ions].
\( \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \)
[contains - molecules and ions]

(2) Strong Alkali – Is an alkali which dissociates – almost completely in aqueous solution thereby producing a – high concentration of hydroxyl [\( \text{OH}^- \)] ions.
Examples: Lithium, Sodium and Potassium hydroxide.
\( \text{NaOH [aq]} \rightleftharpoons \text{Na}^+ + \text{OH}^- \)
\( \text{KOH [aq]} \rightleftharpoons \text{K}^+ + \text{OH}^- \)
[contains almost - only ions]

Weak alkali – Is an alkali which dissociates – only partially in aqueous solution thereby producing a – low concentration of hydroxyl [\( \text{OH}^- \)] ions.
\( \text{NH}_4\text{OH [aq]} \rightleftharpoons \text{NH}_4^+ + \text{OH}^- \)
[contains - molecule and ions]

Examples: Ammonium hydroxide and Calcium hydroxide.

Question. Name the ions formed when – \( \text{HCl} \) ; \( \text{HNO}_3 \) ; \( \text{H}_2\text{SO}_4 \) ; \( \text{CH}_3\text{COOH} \) ; \( \text{NaOH} \) and \( \text{NH}_4\text{OH} \) ionise in aq. soln.
Answer:
\( \text{HCl (aq)} + \text{H}_2\text{O}(l) \longrightarrow \text{H}_3\text{O}^+(\text{aq)} + \text{Cl}^-\text{(aq)} \)
\( \quad\quad\text{Hydronium ion}\quad\quad\quad\text{Chloride ion} \)
\( \text{HNO}_3\text{(aq)} + \text{H}_2\text{O}(l) \longrightarrow \text{H}_3\text{O}^+(\text{aq)} + \text{NO}_3^-\text{(aq)} \)
\( \quad\quad\text{Hydronium ion}\quad\quad\quad\text{Nitrate ion} \)
\( \text{H}_2\text{SO}_4\text{(aq)} + 2\text{H}_2\text{O}(l) \longrightarrow 2\text{H}_3\text{O}^+(\text{aq)} + \text{SO}_4^{2-}\text{(aq)} \)
\( \quad\quad\text{Hydronium ion}\quad\quad\quad\text{Sulphate ion} \)
\( \text{CH}_3\text{COOH(aq)} + \text{H}_2\text{O}(l) \rightleftharpoons \text{H}_3\text{O}^+(\text{aq)} + \text{CH}_3\text{COO}^-\text{(aq)} \)
\( \quad\quad\text{Hydronium ion}\quad\quad\quad\text{Acetate ion} \)
\( \text{NaOH(aq)} \longrightarrow \text{Na}^+(\text{aq)} + \text{OH}^-\text{(aq)} \)
\( \quad\quad\text{Sodium ion}\quad\quad\quad\text{Hydroxyl ion} \)
\( \text{NH}_4\text{OH(aq)} \rightleftharpoons \text{NH}_4^+\text{(aq)} + \text{OH}^-\text{(aq)} \)
\( \quad\quad\text{Ammonium ion}\quad\quad\quad\text{Hydroxyl ion} \)

Question. State giving reasons which is a stronger acid – dil. \( \text{HCl} \) or conc. \( \text{H}_2\text{CO}_3 \).
Answer:
Dil. \( \text{HCl} \) is a stronger acid than conc. \( \text{H}_2\text{CO}_3 \).
Reason: \( \text{HCl} \) ionises almost completely in aqueous solution thereby producing a high concentration of \( \text{H}_3\text{O}^+ \) ions in aqueous solution. On the other hand, \( \text{H}_2\text{CO}_3 \) ionises to a very small extent producing a low concentration of \( \text{H}_3\text{O}^+ \) ions. More the concentration of \( \text{H}_3\text{O}^+ \) ions in solution, stronger is the acid. Hence dil. \( \text{HCl} \) is a stronger acid than conc. \( \text{H}_2\text{CO}_3 \).

Question. State why the basicity of acetic acid is one and acidity of calcium hydroxide is two.
Answer:
Basicity of an acid is the number of hydrogen ions which can be produced from one molecule of the acids on complete dissociation. Acetic acid, \( \text{CH}_3\text{COOH} \) gives one \( \text{H}^+ \) per molecule the acid, hence acetic acid is monobasic i.e., its basicity is one.
\( \text{CH}_3\text{COOH(aq)} \rightleftharpoons \text{CH}_3\text{COO}^-\text{(aq)} + \text{H}^+\text{(aq)} \)
Acidity of a base is the number of hydroxyl ions which can be produced from one molecule of the base on complete dissociation. \( \text{Ca(OH)}_2 \) (calcium hydroxide) gives two hydroxyl ions per molecule of the base, hence calcium hydroxide is diacidic i.e., its acidity is two.

Question. Give three reasons with equations wherever required, why sulphuric acid is a dibasic acid.
Answer:
Sulphuric acid (\( \text{H}_2\text{SO}_4 \)) is a dibasic acid as explained below:

(1)
It ionises in aqueous solution to produce two hydrogen ions per molecule of the acid.
OR
It contains two replaceable hydrogen ions per molecule of the acid.
\( \text{H}_2\text{SO}_4\text{(aq)} \rightleftharpoons 2\text{H}^+\text{(aq)} + \text{SO}_4^{2-}\text{(aq)} \)

(2)
It ionises in two steps in aqueous solution as shown below:
\( \text{H}_2\text{SO}_4\text{(aq)} + \text{H}_2\text{O}(l) \longrightarrow \text{H}_3\text{O}^+\text{(aq)} + \text{HSO}_4^-\text{(aq)} \)
\( \text{HSO}_4^-\text{(aq)} + \text{H}_2\text{O}(l) \longrightarrow \text{H}_3\text{O}^+\text{(aq)} + \text{SO}_4^{2-}\text{(aq)} \)

\( \text{H}_2\text{SO}_4\text{(aq)} + 2\text{H}_2\text{O}(l) \longrightarrow 2\text{H}_3\text{O}^+\text{(aq)} + \text{SO}_4^{2-}\text{(aq)} \)

(3)
It forms two types of salt, e.g., normal salt and acid salt as shown below:
\( \text{H}_2\text{SO}_4\text{(aq)} + \text{NaOH(aq)} \longrightarrow \text{NaHSO}_4\text{(aq)} + \text{H}_2\text{O}(l) \)
\(\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad \text{Acid salt} \)
\( \text{H}_2\text{SO}_4\text{(aq)} + 2\text{NaOH(aq)} \longrightarrow \text{Na}_2\text{SO}_4\text{(aq)} + 2\text{H}_2\text{O} \)
\(\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad \text{Normal salt} \)

Question. State how acids are defined as per Arrhenius’s and Lowry – Bronsted’s theory.
Answer:
Arrhenius Theory –
Acids are substances which – dissociate in aqueous solution to give \( \text{H}^+ \) ions.
Strong acids dissociate – almost completely, while weak acids dissociate partially.

Question. Oxygen atom in water has two 'lone pair of electrons'. Explain the meaning of the term in italics. With the help of an electron dot diagram show the formation of hydronium ion and ammonium ion from a water molecule and an ammonia molecule respectively.
Answer:
A pair of electrons not shared with any other atom for bond formation is called a lone pair of electrons. In water, the central atom – oxygen has two lone pair of electrons as shown ahead:

Structure of water molecule
\[ \begin{array}{ccc} & \bullet\bullet & \\ \text{H} & \text{O} & \text{H} \\ & \bullet\bullet & \end{array} \quad \text{Or} \quad \begin{array}{rcc} & \bullet\bullet & \\ \text{H} & - & \text{O} & \leftarrow \text{Two lone pairs of electrons} \\ & & | & \\ & & \text{H} & \end{array} \]

Formation of hydronium ion - (\( \text{H}_3\text{O}^+ \)): When an acid is dissolved in water the proton (\( \text{H}^+ \)) released by the acid add onto the lone pair electrons of the oxygen atom of a water molecule. The proton (\( \text{H}^+ \)) accepts the lone pair of electrons forming a coordinate bond (shown by an arrow).
\( \text{HCl} \longrightarrow \text{H}^+ + \text{Cl}^- \)
\[ \begin{array}{ccccc} \text{H} - \ddot{\text{O}} : & + & \text{H}^+ & \longrightarrow & \text{H} - \ddot{\text{O}}^+ \rightarrow \text{H} \\ | & & & & | \\ \text{H} & & & & \text{H} \\ \text{Water} & & \text{Proton} & & \text{Hydronium ion} \end{array} \]

Formation of ammonium ion (\( \text{NH}_4^+ \)): When ammonia gas is dissolved in water, the proton released by water adds onto the lone pair of electrons of the nitrogen atom of the ammonia molecule. The proton (\( \text{H}^+ \)) accepts the lone pair of electrons forming a coordinate bond (shown by an arrow).
\( \text{H}_2\text{O} \rightleftharpoons \text{H}^+ + \text{OH}^- \)
\[ \begin{array}{ccccc} \text{H} - \ddot{\text{O}} : & + & \text{H}^+ & \longrightarrow & \text{H} - \ddot{\text{O}}^+ \rightarrow \text{H} \\ | & & & & | \\ \text{H} & & & & \text{H} \\ \text{Water} & & \text{Proton} & & \text{Hydronium ion} \end{array} \]

Question. State how you would obtain:
1. Sulphuric acid from an acidic oxide
2. KOH from a basic oxide.
Answer:
(1) Sulphuric acid from acidic oxide
\( \text{SO}_3 + \text{H}_2\text{O} \longrightarrow \text{H}_2\text{SO}_4 \)
\( \text{Sulphur trioxide} \quad\quad\quad \text{Sulphuric acid} \)
\( \text{(Acidic oxide)} \)

(2) KOH from basic oxide
\( \text{K}_2\text{O} + \text{H}_2\text{O} \longrightarrow 2\text{KOH} \)
\( \text{Potassium oxide} \quad\quad\quad \text{Potassium hydroxide} \)
\( \text{(Basic oxide)} \)

Question. State two chemical properties each with equations of a solution containing
(1) \( \text{H}^+ \) ions
(2) \( \text{OH}^- \) ions
Answer:
(1) Properties of a solution containing \( \text{H}^+ \) ions: Acids when dissolved in water produce \( \text{H}_3\text{O}^+ \) or \( \text{H}^+ \) ions. Typical chemical properties of aqueous solution of acids are:

(a) Neutralisation: \( \text{H}^+ \) ions react with \( \text{OH}^- \) ions from alkalies to give water
\( \text{H}^+ + \text{OH}^- \longrightarrow \text{H}_2\text{O} \)
\( \text{(From acid)} \quad \text{(From alkali)} \quad\quad \text{Water} \)

(b) Reaction with active metals: Active metals like \( \text{Al, Zn, Fe} \), etc., react with dil. acids (\( \text{HCl, H}_2\text{SO}_4 \)) to give hydrogen gas. In this reaction \( \text{H}^+ \) is reduced to \( \text{H}_2 \), by the active metal. For example,
\( \text{Zn} \longrightarrow \text{Zn}^{2+} + 2e^- \)
\( 2\text{H}^+ + 2e^- \longrightarrow \text{H}_2\uparrow \)

\( \text{Zn} + 2\text{H}^+ \longrightarrow \text{Zn}^{2+} + \text{H}_2 \)

(2) Properties of solution containing \( \text{OH}^- \) ions: Alkalies when dissolved in water produce \( \text{OH}^- \) ions. Typical reaction of aqueous solution of alkalies are;

(a) Neutralisation: \( \text{OH}^- \) ions react with \( \text{H}^+ \) ions from acids to give water.
\( \text{OH}^- + \text{H}^+ \longrightarrow \text{H}_2\text{O} \)
\( \text{(From alkalies)} \quad \text{(From acids)} \quad\quad \text{Water} \)

(b) Reaction with solutions of metallic salts: Hydroxides of metals other than Group 1 and 2 are generally insoluble in water. Such hydroxides are precipitated from their respective salt solutions by \( \text{OH}^- \) ions. For example,
\( \text{Fe}^{3+} + 3\text{OH}^- \longrightarrow \text{Fe(OH)}_3 \)
\( \text{(From FeCl}_3\text{)} \quad\quad\quad\quad \text{Red brown ppt.} \)

Question. Give equations for the decomposition of a metallic
(1) chloride
(2) nitrate with conc. \( \text{H}_2\text{SO}_4 \).
Answer:
(1) Reaction of conc. \( \text{H}_2\text{SO}_4 \) with metallic chloride:
\( \text{NaCl}(s) + \text{H}_2\text{SO}_4(\text{conc.}) \xrightarrow{<200^\circ\text{C}} \text{NaHSO}_4 + \text{HCl}\uparrow \)
\( 2\text{NaCl}(s) + \text{H}_2\text{SO}_4(\text{conc.}) \xrightarrow{>200^\circ\text{C}} \text{Na}_2\text{SO}_4 + 2\text{HCl}\uparrow \)

(2) Reaction of conc. \( \text{H}_2\text{SO}_4 \) with metallic nitrate:
\( \text{KNO}_3(s) + \text{H}_2\text{SO}_4(\text{conc.}) \xrightarrow{<200^\circ\text{C}} \text{KHSO}_4 + \text{HNO}_3\uparrow \)
\( 2\text{KNO}_3(s) + \text{H}_2\text{SO}_4(\text{conc.}) \xrightarrow{>200^\circ\text{C}} \text{K}_2\text{SO}_4 + 2\text{HNO}_3\uparrow \)

Question. State in the above reactions a reason for the formation of the respective acids from conc. \( \text{H}_2\text{SO}_4 \).
Answer:
The reason for the formation of the respective acids from conc. \( \text{H}_2\text{SO}_4 \) is the volatility of the acid formed. At room temperature or above \( \text{HCl} \) is a gas while \( \text{HNO}_3 \), which is a liquid at room temperature, volatilises at the reaction temperature (\( \approx 200^\circ\text{C} \)).

Question. Convert
(1) \( \text{NaHCO}_3 \)
(2) \( \text{Na}_2\text{CO}_3 \) to unstable carbonic acid by action with dil. \( \text{H}_2\text{SO}_4 \).
State the reason why ammonia is evolved when an ammonium salt and alkali are heated.
Answer:
1. \( 2\text{NaHCO}_3 + \text{H}_2\text{SO}_4\text{ (dil.)} \longrightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{CO}_3 \)
2. \( \text{Na}_2\text{CO}_3 + \text{H}_2\text{SO}_4\text{ (dil.)} \longrightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{CO}_3 \)

Ammonia is evolved when an ammonium salt and alkali are heated.
\( 2\text{NH}_4\text{Cl}(s) + \text{Ca(OH)}_2(s) \xrightarrow{\Delta} \text{CaCl}_2(s) + 2\text{H}_2\text{O}(g) + 2\text{NH}_3(g) \)
This is because a non-volatile base, \( \text{Ca(OH)}_2 \) displaces a volatile base, \( \text{NH}_4\text{OH} \) which decomposes to give \( \text{NH}_3 \) and \( \text{H}_2\text{O} \).

Question. Define pH value. What would you say about the pH of a solution in which (i) \( \text{H}^+ \) ions = \( \text{OH}^- \) ions
1. evolves \( \text{CO}_2 \) when heated with \( \text{Na}_2\text{CO}_3 \)
2. \( \text{OH}^- \) ions > \( \text{H}^+ \) ions.
Answer:
pH value: The pH value of a solution is defined as the negative logarithm (to the base 10) of the hydrogen ion concentration expressed in \( \text{mol L}^{-1} \). Thus,
\( \text{pH} = -\log_{10} [\text{H}^+] \)
Where \( [\text{H}^+] \) stands for hydrogen ion concentration in \( \text{mol L}^{-1} \).

1. A solution in which \( [\text{H}^+] = [\text{OH}^-] \), is neutral with \( \text{pH} = 7 \).
2. A solution which evolves \( \text{CO}_2 \) with \( \text{Na}_2\text{CO}_3 \) is acidic in nature with \( \text{pH} < 7 \).
3. A solution in which \( [\text{OH}^-] > [\text{H}^+] \) is basic in nature with \( \text{pH} > 7 \).

Question. State whether litmus is a common acid-base indicator or a universal indicator.
Answer:
Litmus is a common acid-base indicator. It is not a universal indicator.

Question. State the colour change in a neutral litmus in presence of
(1) acidic
(2) alkaline medium.
Answer:
Neutral litmus is purple in colour
1. In acidic medium colour of neutral litmus changes from purple to red.
2. In alkaline medium colour of neutral litmus changes from purple to blue.

Question. State the colour change in a universal indicator e.g. pH paper on
1. slightly acidic soil
2. slightly alkaline soil
3. dairy milk
4. human blood tested for medical diagnosis.
Answer:
1. In slightly acidic soil colour of universal indicator changes to yellow.
2. In slightly alkaline soil colour of universal indicator changes to blue.
3. In dairy milk colour of universal indicator change to green.
4. In human blood colour of universal indicator changes to green (\( \text{pH} = 7.3 \)).

Question. Define
(1) salt
(2) normal salt
(3) acid salt – with relevant examples and equations.
Answer:
(1) Salts: A salt is a compound formed by partial or complete replacement of the replaceable hydrogen ions of an acid by a metallic ion or ammonium ion.
\( \text{NaOH(aq)} + \text{H}_2\text{SO}_4\text{(aq)} \longrightarrow \text{NaHSO}_4\text{(aq)} + \text{H}_2\text{O}(l) \)
\( \quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad \text{(Partial replacement)} \)
\( 2\text{NaOH(aq)} + \text{H}_2\text{SO}_4\text{(aq)} \longrightarrow \text{Na}_2\text{SO}_4\text{(aq)} + 2\text{H}_2\text{O}(l) \)
\( \quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad \text{(Complete replacement)} \)

(2) Normal salt: The salt formed by complete replacement of the replaceable hydrogen ions present in a molecule of the acid by metallic or ammonium ion. For example,
\( 2\text{NaOH(aq)} + \text{H}_2\text{SO}_4\text{(aq)} \longrightarrow \text{Na}_2\text{SO}_4\text{(aq)} + 2\text{H}_2\text{O}(l) \)
\( \quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad \text{(Normal Salt)} \)
\( 2\text{NaOH(aq)} + \text{H}_2\text{CO}_3\text{(aq)} \longrightarrow \text{Na}_2\text{CO}_3\text{(aq)} + 2\text{H}_2\text{O}(l) \)
\( \text{NH}_4\text{OH(aq)} + \text{HCl(aq)} \longrightarrow \text{NH}_4\text{Cl(aq)} + \text{H}_2\text{O}(l) \)

(3) Acid salt: The salt formed by partial replacement of the replaceable hydrogen ions present in a molecule of the acid by metallic or ammonium ion. For example,
\( \text{NaOH(aq)} + \text{H}_3\text{PO}_4\text{(aq)} \longrightarrow \text{NaH}_2\text{PO}_4\text{(aq)} + \text{H}_2\text{O}(l) \)
\( 2\text{NaOH(aq)} + \text{H}_3\text{PO}_4\text{(aq)} \longrightarrow \text{Na}_2\text{HPO}_4\text{(aq)} + 2\text{H}_2\text{O}(l) \)
\( \text{KOH(aq)} + \text{H}_2\text{SO}_4\text{(aq)} \longrightarrow \text{KHSO}_4\text{(aq)} + \text{H}_2\text{O}(l) \)
\( \text{NH}_4\text{OH(aq)} + \text{H}_2\text{CO}_3\text{(aq)} \longrightarrow \text{NH}_4\text{HCO}_3\text{(aq)} + \text{H}_2\text{O}(l) \)

Question. State:
1. the formation
2. the components of – a basic salt.

State which of following salts is an – acid, normal or basic salt.
1. bleaching powder
2. potassium mercuric iodide
3. sodium sulphite
4. sodium hydrogen sulphite
5. sodium silver cyanide
6. basic lead nitrate
7. potassium zincate
8. alum
9. calcium bicarbonate
10. basic copper chloride
11. trisodium phosphate.
Answer:
(1) Formation of a basic salt: A basic salt is formed by partial replacement of hydroxyl group of a diacidic or triacidic base with an acid radical (or an anion other than \( \text{OH}^- \)).

(2) Components of a basic salt: A basic salt contains a cation (other than \( \text{H}^+ \) ion), a hydroxyl ion (\( \text{OH}^- \) from base) and an anion (other than \( \text{OH}^- \) ion). For

Examples:

• Basic copper nitrate: \( \text{Cu(OH)NO}_3 \)
• Basic copper chloride: \( \text{Cu(OH)Cl} \)
• Bleaching powder, \( \text{CaOCl} \), (Normal salt/Mixed salt)
• Potassium mercuric iodide, \( \text{K}_2(\text{HgI}_4) \), (Normal salt/Complex salt)
• Sodium sulphate, \( \text{Na}_2\text{SO}_4 \) (Normal salt)
• Sodium hydrogen sulphite, \( \text{NaHSO}_3 \) (Acid salt)
• Sodium silver cyanide, \( \text{Na[Ag(CN)}_2] \) (Normal salt/Complex salt)
• Basic lead nitrate, \( \text{Pb(OH)NO}_3 \) (Basic salt)
• Potassium zincate, \( \text{K}_2\text{ZnO}_2 \) (Normal salt)
• Alum or potash alum, \( \text{K}_2\text{SO}_4\cdot\text{Al}_2(\text{SO}_4)_3\cdot24\text{H}_2\text{O} \) (Normal salt/Double salt)
• Calcium bicarbonate, \( \text{Ca(HCO}_3)_2 \) (Acid salt)
• Basic copper chloride, \( \text{Cu(OH)Cl} \) (Basic salt)
• Trisodium phosphate, \( \text{Na}_3\text{PO}_4 \) (Normal salt)

Question. Name three (1) sulphates (2) chlorides insoluble in water and – two (1) oxides (2) carbonates soluble in water.
Answer:
(1) Three sulphates insoluble in water
Lead sulphate (\( \text{PbSO}_4 \)), Calcium sulphate (\( \text{CaSO}_4 \)), and Barium sulphate (\( \text{BaSO}_4 \)).

(2) Three chloride insoluble in water
Silver chloride (\( \text{AgCl} \)), Lead chloride (\( \text{PbCl}_2 \)), and Mercury chloride (\( \text{Hg}_2\text{Cl}_2 \) or \( \text{HgCl} \)).

(1) Two oxides soluble in water
Sodium oxide (\( \text{Na}_2\text{O} \)), and Potassium oxide (\( \text{K}_2\text{O} \))

(2) Two carbonates soluble in water
Sodium carbonate (\( \text{Na}_2\text{CO}_3 \)), and Ammonium carbonate (\( [(\text{NH}_4)_2\text{CO}_3] \))

Question. State the method only, generally used for the preparation of the following salts
(1) \( \text{Zn(NO}_3)_2 \)
(2) \( \text{NH}_4\text{Cl} \)
(3) \( \text{ZnSO}_4 \)
(4) \( \text{ZnS} \)
(5) \( \text{CaCO}_3 \)
(6) \( \text{FeCl}_3 \)
(7) \( \text{PbCl}_2 \)
(8) \( \text{Pb(NO}_3)_2 \)
Answer:

Question. Give balanced equations for the preparation of the following salts –
(a)
(1) \( \text{CuSO}_4 \)
(2) \( \text{NaHSO}_4 \)
(3) \( \text{Na}_2\text{SO}_4 \)
(4) \( \text{FeSO}_4 \)
(5) \( \text{BaSO}_4 \)
(6) \( \text{PbSO}_4 \) – using dil. \( \text{H}_2\text{SO}_4 \)
(b)
(1) \( \text{NaHSO}_4 \)
(2) \( \text{CuSO}_4 \) – using conc. \( \text{H}_2\text{SO}_4 \)
Answer:
(a) Using dil. \( \text{H}_2\text{SO}_4 \)
1. \( \text{CuO (s)} + \text{H}_2\text{SO}_4 \text{ (aq)} \rightarrow \text{CuSO}_4 \text{ (aq)} + \text{H}_2\text{O (l)} \)
2. \( \text{NaOH (aq)} + \text{H}_2\text{SO}_4 \text{ (aq)} \rightarrow \text{NaHSO}_4 \text{ (aq)} + \text{H}_2\text{O (l)} \)
3. \( 2\text{NaOH (aq)} + \text{H}_2\text{SO}_4 \text{ (aq)} \rightarrow \text{Na}_2\text{SO}_4 \text{ (aq)} + 2\text{H}_2\text{O (l)} \)
4. \( \text{Fe (s)} + \text{H}_2\text{SO}_4 \text{ (aq)} \rightarrow \text{FeSO}_4 \text{ (aq)} + \text{H}_2 \text{ (g)} \)
5. \( \text{BaCl}_2 \text{ (aq)} + \text{H}_2\text{SO}_4 \text{ (aq)} \rightarrow \text{BaSO}_4 \text{ (s)} + 2\text{HCl (aq)} \)
6. \( \text{Pb(NO}_3)_2 + \text{H}_2\text{SO}_4 \text{ (aq)} \rightarrow \text{PbSO}_4 \text{ (s)} + 2\text{HNO}_3 \text{ (aq)} \)

(b) Using conc. \( \text{H}_2\text{SO}_4 \)
(1) \( \text{NaOH (aq)} + \text{H}_2\text{SO}_4 \text{ (conc.)} \rightarrow \text{NaHSO}_4 \text{ (aq)} + \text{H}_2\text{O (l)} \)
(2) \( \text{Cu (s)} + 2\text{H}_2\text{SO}_4 \text{ (conc.)} \xrightarrow{\Delta} \text{CuSO}_4 \text{ (aq)} + \text{SO}_2 \text{ (g)} + 2\text{H}_2\text{O (l)} \)
     \( \text{CuO (s)} + \text{H}_2\text{SO}_4 \text{ (conc.)} \rightarrow \text{CuSO}_4 \text{ (aq)} + \text{H}_2\text{O (l)} \)

Question. Starting from insoluble \( \text{ZnO} \) how would you obtain insoluble \( \text{ZnCO}_3 \) by precipitation.
Answer:
\( \text{ZnO (s)} + 2\text{HCl (aq)} \rightarrow \text{ZnCl}_2 \text{ (aq)} + \text{H}_2\text{O (l)} \)
\( \text{ZnCl}_2 \text{ (aq)} + \text{Na}_2\text{CO}_3 \text{ (aq)} \rightarrow \text{ZnCO}_3 \text{ (s)} + 2\text{NaCl (aq)} \)

Dissolve zinc oxide in minimum quantity of dil. \( \text{HCl} \). Add to it a saturated solution of \( \text{Na}_2\text{CO}_3 \) in water till no more precipitation takes place. Filter and dry the \( \text{ZnCO}_3 \) so obtained.

Question. Give balanced equations for the action of a dilute acid on
(1) zinc carbonate,
(2) potassium bicarbonate for the preparation of the respective salt.
Answer:
1. Zinc carbonate
\( \text{ZnCO}_3 + 2\text{HNO}_3 \rightarrow \text{Zn(NO}_3)_2 + \text{H}_2\text{O} + \text{CO}_2 \)

2. Potassium bicarbonate
\( 2\text{KHCO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{K}_2\text{SO}_4 + 2\text{H}_2\text{O} + 2\text{CO}_2 \)

Question. Give balanced equations for the decomposition of
(1) calcium bicarbonate by dil. \( \text{HCl} \),
(2) calcium carbonate by dil. \( \text{HNO}_3 \),
(3) sodium sulphite by dil. \( \text{H}_2\text{SO}_4 \),
(4) zinc sulphide by dil. \( \text{H}_2\text{SO}_4 \).
Answer:
1. \( \text{Ca(HCO}_3)_2 + 2\text{HCl} \rightarrow \text{CaCl}_2 + 2\text{H}_2\text{O} + 2\text{CO}_2 \)
2. \( \text{CaCO}_3 + 2\text{HNO}_3 \rightarrow \text{Ca(NO}_3)_2 + \text{H}_2\text{O} + \text{CO}_2 \)
3. \( \text{Na}_2\text{SO}_3 + \text{H}_2\text{SO}_4 \text{ (dil.)} \rightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{O} + \text{SO}_2 \)
4. \( \text{ZnS} + \text{H}_2\text{SO}_4 \rightarrow \text{ZnSO}_4 + \text{H}_2\text{S} \)

Question. State what will be the effect of each of the following solution on blue litmus –
(1) \( \text{K}_2\text{CO}_3 \) soln
(2) \( \text{KCl} \) soln.
(3) \( \text{NH}_4\text{NO}_3 \)
Answer:
1. \( \text{K}_2\text{CO}_3 \) is a salt of a strong base (\( \text{KOH} \)) and weak acid (\( \text{H}_2\text{CO}_3 \)). Hence its aqueous solution will be basic in nature. It will have no effect on blue litmus solution.
2. \( \text{KCl} \) is a salt of a strong acid (\( \text{HCl} \)) and a strong base (\( \text{KOH} \)). Hence its aqueous solution will be neutral in nature. It will have no effect on blue litmus solution.
3. \( \text{NH}_4\text{NO}_3 \) is a salt of a strong acid (\( \text{HNO}_3 \)) and weak base (\( \text{NH}_4\text{OH} \)). Hence its aqueous solution will be acidic in nature. It will turn blue litmus solution red.