CBSE Class 10 Science Acids Bases and Salts Assignment Set 06

Question. Select the correct acid, base or salt from the list in bracket for each of the statements given below:

Question. An example of an acid derived from a mineral is
(a) citric acid
(b) nitric acid
(c) acetic acid
Answer: (b) nitric acid

Question. An example of a base which is not an alkali is
(a) caustic soda
(b) zinc hydroxide
(c) liquor ammonia
(d) caustic potash
Answer: (b) zinc hydroxide

Question. An example of a strong acid is dilute
(a) acetic acid
(b) sulphuric acid
(c) tartaric acid
(d) carbonic acid
Answer: (b) sulphuric acid

Question. An example of a weak alkali is
(a) potassium hydroxide solution
(b) calcium hydroxide solution
(c) sodium hydroxide solution
Answer: (b) calcium hydroxide solution

Question. An acid having basicity 1 is
(a) carbonic acid
(b) acetic acid
(c) sulphurous acid
Answer: (b) acetic acid

Question. An acid obtained by dissolving sulphur trioxide in water is
(a) sulphurous acid
(b) sulphuric acid
(c) oleum
Answer: (b) sulphuric acid

Question. A volatile acid obtained when nitre reacts with nonvolatile concentrated sulphuric acid on heating is
(a) hydrochloric acid
(b) sulphuric acid
(c) nitric acid
Answer: (c) nitric acid

Question. A base obtained when lead nitrate undergoes thermal decomposition is
(a) trilead tetroxide
(b) lead (IV) oxide
(c) lead (II) oxide
Answer: (c) lead (II) oxide

Question. An acid obtained when concentrated nitric acid is heated with sulphur is
(a) sulphurous acid
(b) sulphuric acid
(c) nitrous acid
Answer: (b) sulphuric acid

Question. The more volatile acid obtained when the less volatile acid reacts with sodium bicarbonate is
(a) sulphuric acid
(b) carbonic acid
(c) nitric acid
Answer: (b) carbonic acid

Question. The insoluble base obtained when sodium hydroxide reacts with iron (III) chloride is
(a) iron (II) hydroxide
(b) iron (III) hydroxide
(c) iron (II) oxide
Answer: (b) iron (III) hydroxide

Question. A solution whose pH is above 7 is
(a) vinegar
(b) milk
(c) liquor ammonia
Answer: (c) liquor ammonia

Question. The salt formed when sulphuric acid reacts with excess caustic soda solution is
(a) sodium bisulphite
(b) sodium sulphate
(c) sodium sulphite
(d) sodium bisulphate
Answer: (b) sodium sulphate

Question. An example of an acid salt is
(a) \( \text{CH}_3\text{COONa} \)
(b) \( \text{NaNO}_3 \)
(c) \( \text{Na}_2\text{HPO}_4 \)
(d) \( \text{NaKCO}_3 \)
Answer: (c) \( \text{Na}_2\text{HPO}_4 \)

Question. An example of a soluble salt is
(a) \( \text{AgCl} \)
(b) \( \text{PbSO}_4 \)
(c) \( \text{CaSO}_4 \)
(d) \( \text{CaCl}_2 \)
Answer: (d) \( \text{CaCl}_2 \)

Question. An example of an insoluble salt is
(a) \( \text{Na}_2\text{CO}_3 \)
(b) \( \text{K}_2\text{CO}_3 \)
(c) \( \text{MgCO}_3 \)
(d) \( (\text{NH}_4)_2\text{CO}_3 \)
Answer: (c) \( \text{MgCO}_3 \)

Question. A salt prepared by neutralization in which titration is involved is
(a) \( \text{MgCl}_2 \)
(b) \( \text{CaCl}_2 \)
(c) \( \text{NH}_4\text{Cl} \)
(d) \( \text{CuCl}_2 \)
Answer: (c) \( \text{NH}_4\text{Cl} \)

Question. An insoluble salt prepared by direct combination or synthesis is
(a) \( \text{FeCl}_3 \)
(b) \( \text{FeSO}_4 \)
(c) \( \text{FeS} \)
(d) \( \text{Fe(NO}_3)_2 \)
Answer: (c) \( \text{FeS} \)

Question. A salt prepared by precipitation i.e. by double decomposition of two salt solutions is
(a) \( \text{Na}_2\text{SO}_4 \)
(b) \( \text{PbSO}_4 \)
(c) \( \text{ZnSO}_4 \)
(d) \( \text{CuSO}_4 \)
Answer: (b) \( \text{PbSO}_4 \)

Question. A salt prepared by simple displacement i.e. action of dilute acid on a metal is
(a) \( \text{PbCl}_2 \)
(b) \( \text{CuCl}_2 \)
(c) \( \text{AlCl}_3 \)
(d) \( \text{HgCl} \)
Answer: (c) \( \text{AlCl}_3 \)

Question. Decomposition of calcium hydrogen carbonate with
(a) dil. \( \text{HNO}_3 \)
(b) dil. \( \text{HCl} \)
(c) dil. \( \text{H}_2\text{SO}_4 \)
results in formation of calcium chloride.
Answer: (b) dil. \( \text{HCl} \)

Question. Action of dilute acid on a metallic sulphide results in evolution of
(a) \( \text{SO}_2 \)
(b) \( \text{H}_2\text{S} \)
(c) \( \text{CO}_2 \)
gas.
Answer: (b) \( \text{H}_2\text{S} \)

Question. A salt which on hydrolysis produces a neutral solution is
(a) sodium chloride
(b) ammonium chloride
(c) sodium carbonate
Answer: (a) sodium chloride

Unit Test Paper 3 A — Acids, Bases and Salts

I. Name the following:

Question. A basic solution which does not contain a metallic element.
Answer: Ammonium Hydroxide.

Question. A normal salt of sodium formed from acetic acid.
Answer: Sodium acetate, \( \text{CH}_3\text{COONa} \).

Question. A base which reacts with an acid to give a salt which on hydrolysis gives a slightly acidic solution.
Answer: Ammonium hydroxide (\( \text{NH}_4\text{OH} \)) OR Calcium hydroxide (\( \text{Ca(OH)}_2 \)).

Question. An ion which combines with a polar covalent molecule to form an ammonium ion.
Answer: Hydrogen ion / a proton (\( \text{H}^+ \)).

Question. A soluble salt formed by direct combination between a light metal & a greenish yellow gas.
Answer: \( \text{AlCl}_3 \).

II. Identify which of the following terms matches with the appropriate description:

Terms:
A: Hydracid
B: Monobasic acid
C: Less volatile acid
D: Weak acid
E: Tribasic acid
F: Dibasic acid
G: More volatile acid

Question. An acid having basicity 1 and having only one replaceable hydrogen ion per molecule of the acid.
Answer: Monobasic acid

Question. An acid which dissociates to give a low concentration of \( \text{H}^+ \)
Answer: Weak acid

Question. An acid containing hydrogen and a non-metallic element other than oxygen.
Answer: Hydracids

Question. The type of acid which generally displaces another acid when the acid is heated with a salt.
Answer: Less volatile acid

Question. The type of acid which reacts with a base to give an acid salt and a normal salt.
Answer: Dibasic acid

III. State which of the following methods is generally used for preparing the salts:

Methods:
A: Neutralisation – insoluble base and dil. acid
B: Neutralisation – alkali and dil. acid
C: Simple displacement – active metal and dil. acid
D: Direct combination
E: Precipitation (double decomposition)

Question. State which method is generally used for preparing: \( \text{PbCO}_3 \)
Answer: Precipitation (double decomposition) (E)

Question. State which method is generally used for preparing: \( \text{Zn(NO}_3)_2 \)
Answer: Simple displacement – active metal and dil. acid (C)

Question. State which method is generally used for preparing: \( \text{NaCl} \)
Answer: Neutralisation – alkali and dil. acid (B)

Question. State which method is generally used for preparing: \( \text{Cu(NO}_3)_2 \)
Answer: Neutralisation + insoluble base and dil. acid (A)

Question. State which method is generally used for preparing: \( \text{FeS} \)
Answer: Direct combination (D)

IV. Give balanced equations for the preparation of the following salts:

Question. Calcium oxide \( \rightarrow \) Calcium chloride \( \rightarrow \) Calcium carbonate
Answer: \( \text{CaO} + 2\text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2\text{O} \)

Question. Zinc sulphide \( \text{Zn} \rightarrow \) Zinc sulphate
Answer: \( \text{Zn} + \text{S} \rightarrow \text{ZnS} \)

Question. Iron (II) chloride \( \leftarrow \text{Fe} \rightarrow \) Iron (III) chloride
Answer: \( \text{Fe} + 2\text{HCl} \rightarrow \text{FeCl}_2 + \text{H}_2 \)

Question. Lead (II) oxide \( \rightarrow \) Lead nitrate \( \rightarrow \) Lead sulphate
Answer: \( \text{PbO} + 2\text{HNO}_3 \rightarrow \text{Pb(NO}_3)_2 + \text{H}_2\text{O} \)

Question. Copper (II) oxide \( \rightarrow \) Copper (II) sulphate \( \leftarrow \) Copper (II) hydroxide
Answer: \( \text{CuO} + \text{H}_2\text{SO}_4 \rightarrow \text{CuSO}_4 + \text{H}_2\text{O} \)

V. Preparation of Sodium Sulphate Salt

The diagram represents the preparation of sodium sulphate salt from dil. \( \text{H}_2\text{SO}_4 \) acid and sodium hydroxide.

Question. Name the apparatus 'A'.
Answer: Burette

Question. Name the substance 'X' placed in 'A' and the substance 'Y' placed in B.
Answer: Dil. \( \text{H}_2\text{SO}_4 \), Sodium Hydroxide

Question. State the reason for conducting the titration using the apparatus 'A' and 'B'.
Answer: Titration is conducted to determine the completion of the neutralisation reaction, i.e., to determine the amount of sulphuric acid required to neutralise a known amount of sodium hydroxide.

Question. State which solution is transferred to the evaporating dish and evaporated to point of crystallisation for obtaining the salt.
Answer: Sodium Sulphate.

Question. State why titration is not conducted for the preparation of copper (II) sulphate crystals by neutralisation.
Answer: This is because copper (II) oxide is not soluble in water.

Give reasons for the following:

Question. Concentrated sulphuric acid is a weaker acid compared to dilute sulphuric acid.
Answer: Sulphuric acid, \( \text{H}_2\text{SO}_4 \) is a covalent compound as shown below:
\( \text{H}-\text{O}-\text{SO}_2-\text{O}-\text{H} \)
When dissolved in water, polar water molecules help in its ionisation, thus producing \( \text{H}_3\text{O}^+ \) ions responsible for its acidic nature. More water (i.e., dilute acid) means more \( \text{H}_3\text{O}^+ \) ions and hence stronger acid.

Question. An aqueous solution of the salt ammonium chloride is acidic in nature while an aqueous solution of sodium chloride is neutral.
Answer:
\( \text{NH}_4\text{Cl} + \text{H}_2\text{O} \rightarrow \text{NH}_4\text{OH [weak alkali]} + \text{HCl [strong acid]} \)

\( \text{NaCl} + \text{H}_2\text{O} \rightarrow \text{NaOH [strong alkali]} + \text{HCl [strong acid]} \)

From the above equation it is clear that \( \text{NH}_4\text{Cl} \) forms weak alkali which is acidic in nature whereas \( \text{NaCl} \) from strong alkali which is neutral.

Question. In the preparation of an insoluble salt from another insoluble salt by precipitation [double decomposition], dilute nitric acid and not dilute sulphuric acid is generally used.
Answer: Direct addition of dil. \( \text{H}_2\text{SO}_4 \) to \( \text{PbCO}_3 \) is an impractical method of preparing lead sulphate since \( \text{PbSO}_4 \) is insoluble and forms a coating on \( \text{PbCO}_3 \), thereby the reaction slowly comes to a stop.

Question. Acetic acid does not form an acid salt but forms a normal salt.
Answer: Acetic acid (\( \text{CH}_3\text{COOH} \)) is a monobasic acid, i.e. it contains only one replaceable hydrogen ion per molecule of the acid. As such it can only form normal salts.

Question. Sulphurous acid forms two types of salts on reaction with an alkali.
Answer: Sulphurous acid (\( \text{H}_2\text{SO}_3 \)) is a dibasic acid, i.e., it contains two replaceable hydrogen ions per molecule. As such, it can form normal salt (say \( \text{Na}_2\text{SO}_3 \)) as well as acid salt (\( \text{NaHSO}_3 \)) on reaction with an alkali.

Analytical Chemistry – Use Of Ammonium & Sodium Hydroxide

Question. Write the observations and balanced equations for the following reactions:
1. Sodium hydroxide is added drop-wise till in excess to a solution of zinc sulphate.
2. Ammonium hydroxide is added in excess to a solution of copper sulphate.
Answer:
(1) A white ppt formed redissolves in excess of sodium hydroxide solution.
\( \text{ZnSO}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + \text{Zn(OH)}_2\downarrow \) (Gel. White ppt.)
\( \text{Zn(OH)}_2 + 2\text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + 2\text{H}_2\text{O} \) (Sodium zincate - White solution)

(2) Pale blue ppt formed dissolves in excess of ammonium hydroxide solution to form deep blue solution.
\( \text{CuSO}_4 + 2\text{NH}_4\text{OH} \rightarrow (\text{NH}_4)_2\text{SO}_4 + \text{Cu(OH)}_2\downarrow \)
\( \text{Cu(OH)}_2 + (\text{NH}_4)_2\text{SO}_4 + 2\text{NH}_4\text{OH} \rightarrow [\text{Cu(NH}_3)_4]\text{SO}_4 + 4\text{H}_2\text{O} \) (Tetra-amine copper (II) sulphate - deep blue colour)

Question. Sodium hydroxide solution is added first in a small amount then in excess to the aqueous salt solutions of
(a) copper [II] sulphate,
(b) zinc nitrate,
(c) lead nitrate,
(d) iron
State in each case:
1. the colour of the precipitate when NaOH is added in a small quantity;
2. the nature of the precipitate (i.e. soluble or insoluble) when NaOH is added in excess.
Answer:
(1) Colour of the precipitate when NaOH is added in small quantity:
(a) Blue
(b) White
(c) White
(d) Reddish brown

(2) Nature of the precipitate when NaOH is added in excess:
(a) Insoluble
(b) Soluble
(c) Soluble
(d) Insoluble.

Question. Write balanced equations for –
(a) Aluminium
(b) Zinc – is warmed with NaOH (caustic soda)
Answer:
(a) \( \text{Al} + 2\text{NaOH} + 2\text{H}_2\text{O} \rightarrow 2\text{NaAlO}_2 + 3\text{H}_2 \)
(b) \( \text{Zn} + 2\text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + \text{H}_2 \)

The questions below refers to the following salt solutions listed A to F:
A: Copper nitrate, B: Iron [II] sulphate, C: Iron [III] chloride, D: Lead nitrate, E: Magnesium sulphate, F: Zinc chloride.

Question. Which soln. becomes a deep/inky blue colour when excess of ammonium hydroxide is added to it.
Answer: A: Copper nitrate

Question. Which solution gives a white precipitate with excess ammonium hydroxide solution.
Answer: D: Lead nitrate

Question. From the list of substances given – Ammonium sulphate, Lead carbonate, Chlorine, Copper nitrate, ferrous sulphate - State a solution of the compound which gives a dirty green precipitate with sodium hydroxide.
Answer: Ferrous sulphate

Question. Write a balanced equation for the reaction between – aluminium oxide and sodium hydroxide.
Answer: \( \text{Al}_2\text{O}_3 + 2\text{NaOH} \rightarrow 2\text{NaAlO}_2 + \text{H}_2\text{O} \)

Question. Give one test to distinguish between the following – Iron (III) chlorine soln. and copper chloride solution.
Answer: Add NaOH solution in excess of the two solutions. The one in which white ppt. initially formed dissolves in excess of NaOH solution is \( \text{Zn(NO}_3)_2 \) solution and the other is \( \text{Ca(NO}_3)_2 \) solution.

Question. The salt which in soln. gives a pale green precipitate with NaOH solution and a white ppt. with \( \text{BaCl}_2 \) soln. is:
(a) Iron (III) sulphate
(b) Iron (II) sulphate
(c) Iron (II) chloride
(d) Iron (III) chloride
Answer: (b) Iron (II) sulphate

Question. Find the odd one with reason (note: valency is not a criterion):
\( \text{Al(OH)}_3 \), \( \text{Pb(OH)}_2 \), \( \text{Mg(OH)}_2 \), \( \text{Zn(OH)}_2 \)
Answer: \( \text{Mg(OH)}_2 \) [Because all others are amphoteric hydroxides]

Question. Identity the substance P based on the information given below:
The deliquescent salt P, turns yellow on dissolving in water, and gives a reddish brown precipitate with sodium hydroxide solution.
Answer: Ferric chloride.

Question. Give an equation for –
1. ZnO reacts with NaOH solution.
2. Conversion of – \( \text{Zn(NO}_3)_2 \) to \( \text{Zn(OH)}_2 \)
Answer:
(1) \( \text{ZnO} + 2\text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + \text{H}_2\text{O} \) (sodium zincate)

(2) \( \text{Zn(NO}_3)_2 + 2\text{NaOH} \rightarrow \text{Zn(OH)}_2\downarrow + 2\text{NaNO}_3 \) (zinc nitrate, sodium hydroxide, zinc hydroxide, sodium nitrate)

\( \text{Zn(OH)}_2 \xrightarrow{\Delta} \text{ZnO} + \text{H}_2\text{O} \) (zinc hydroxide, zinc oxide, water)

Question. Select the correct answer from A, B, C –
A: Sodium hydroxide soln. B: A weak acid C: Dilute sulphuric acid. The solution which with zinc sulphate solution will give a white precipitate.
Answer: A: Sodium hydroxide soln.

Question. Choose the correct answer from the choices given: Hydroxide of this metal is soluble in NaOH solution.
(a) Magnesium
(b) Lead
(c) Silver
(d) Copper
Answer: (b) Lead

Question. Sodium hydroxide solution is added to the solutions containing the ions mentioned in List 1.
List 1 –
(i) \( \text{Pb}^{2+} \)
(ii) \( \text{Fe}^{2+} \)
(iii) \( \text{Zn}^{2+} \)
(iv) \( \text{Fe}^{3+} \)
(v) \( \text{Cu}^{2+} \)
(vi) \( \text{Ca}^{2+} \)

List 2 – Gives the details of the precipitate.
A: Reddish brown
B: White insoluble in excess
C: Dirty green
D: White soluble in excess
E: White soluble in excess
F: Blue.

Match the ions with their coloured precipitates in List 2.
Answer:
(i) \( \text{Pb}^{2+} \) — D: White soluble in excess
(ii) \( \text{Fe}^{2+} \) — C: Dirty green
(iii) \( \text{Zn}^{2+} \) — D: White soluble in excess
(iv) \( \text{Fe}^{3+} \) — A: Reddish brown
(v) \( \text{Cu}^{2+} \) — F: Blue
(vi) \( \text{Ca}^{2+} \) — B: White insoluble in excess.

Question. Give a balanced chemical equation in each case when–
1. Zinc oxide dissolves in sodium hydroxide.
2. Zinc is heated with NaOH solution.
Answer:
1. \( \text{ZnO} + 2\text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + \text{H}_2\text{O} \)
2. \( \text{Zn} + 2\text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + \text{H}_2\uparrow \)

Question. Name: The gas evolved on reaction of Aluminium with boiling concentrated caustic alkali solution.
Answer: Hydrogen gas

Question. State one observation for:
1. Excess \( \text{NH}_4\text{OH} \) soln. is added to \( \text{Pb(NO}_3)_2 \)
2. NaOH soln. is added to \( \text{FeCl}_3 \) in excess.
Answer:
1. White ppt. insoluble in excess ammonium hydroxide.
2. Reddish brown precipitate is formed which is insoluble in excess of NaOH.

Question. State two relevant observations for the reaction:
Ammonium hydroxide solution is added to copper (II) nitrate solution in small quantities and then in excess.
Answer: With small amount of ammonium hydroxide, a bluish white precipitate is formed. This precipitate dissolves in excess of ammonium hydroxide to form a deep blue solution.

Question. State your observation: When excess sodium hydroxide is added to calcium nitrate solution.
Answer: White ppt. formed is sparingly soluble.
\( \text{Ca(NO}_3)_2 + \text{NaOH} \rightarrow \text{Ca(OH)}_2\downarrow + \text{NaNO}_3 \) (White ppt.)

Question. To a salt solution ‘Y’ a small quantity of ammonium hydroxide solution is added slowly and then in excess. A pale blue precipitate is formed which dissolves in excess to form a clear inky blue solution. Identify the positive ion in the salt ‘Y’
Answer: \( \text{Cu}^{2+} \) (Copper ion)

Question. State your observations when ammonium hydroxide solution is added drop by drop and then in excess to each of the following solutions:
(1) copper sulphate solution
(2) zinc sulphate solution
Answer:
(1)
\( \text{CuSO}_4 + 2\text{NH}_4\text{OH} \rightarrow \text{Cu(OH)}_2\downarrow + (\text{NH}_4)_2\text{SO}_4 \)
(Pale Blue Precipitates)

\( \text{Cu(OH)}_2 + 2(\text{NH}_4)_2\text{SO}_4 + 2\text{NH}_4\text{OH} \rightarrow [\text{Cu(NH}_3)_4]\text{SO}_4 + 4\text{H}_2\text{O} \)
(Deep blue solution)

Pale blue precipitates are formed and then these precipitates dissolve in excess of ammonium hydroxide to form deep blue solution.

(2)
\( \text{ZnSO}_4 + \text{NH}_4\text{OH} \rightarrow \text{Zn(OH)}_2\downarrow + (\text{NH}_4)_2\text{SO}_4 \)
(White gelatinous)

\( \text{Zn(OH)}_2 + (\text{NH}_4)_2\text{SO}_4 + 2\text{NH}_4\text{OH} \rightarrow [\text{Zn(NH}_3)_4]\text{SO}_4 + 4\text{H}_2\text{O} \)
(Colourless)

When ammonium hydroxide is added drop by drop white gelatinous precipitate of zinc hydroxide is formed and on adding excess of ammonium hydroxide colourless solution is formed.

Question. State one relevant observation – Action of sodium hydroxide solution on iron [II] sulphate solution.
Answer: A dirty green precipitate is formed which is insoluble in excess of sodium hydroxide solution.

Question. How will you distinguish between – Ammonium hydroxide & sodium hydroxide using \( \text{CuSO}_4 \)
Answer: Sodium hydroxide forms a pale blue precipitate which is insoluble in excess of sodium hydroxide.
Ammonium hydroxide forms a pale blue precipitate which redissolves in excess of ammonium hydroxide to form deep blue colouration.

Additional Questions

Question. Salts of…………… (normal / transition) elements are generally coloured. From the ions \( \text{K}^+ \), \( \text{Cr}^{3+} \), \( \text{Fe}^{2+} \), \( \text{Ca}^{2+} \), \( \text{SO}_3^{2-} \), \( \text{MnO}_4^{1-} \), \( \text{NO}_3^{1-} \) the ions generally coloured are
Answer: Normal; \( \text{Cr}^{3+} \), \( \text{Fe}^{2+} \), \( \text{MnO}_4^{1-} \)

Question. The hydroxide which is soluble in excess of NaOH is [\( \text{Zn(OH)}_2 \) / \( \text{Fe(OH)}_3 \) / \( \text{Fe(OH)}_2 \)]
Answer: \( \text{Zn(OH)}_2 \)

Question. The salt which will not react with \( \text{NH}_4\text{OH} \) solution [\( \text{ZnCl}_2 \)/\( \text{CuCl}_2 \)/\( \text{NH}_4\text{Cl} \)/\( \text{FeCl}_2 \)]
Answer: \( \text{NH}_4\text{Cl} \)

Question. The substance/s which react/s with hot cone. NaOH soln. and undergoes a neutralization reaction…………….. [\( \text{Al}_2\text{O}_3 \)/Al/\( \text{Al(OH)}_3 \)]
Answer: \( \text{Al}_2\text{O}_3 \)

Question. To distinguish soluble salts of zinc and lead, ……………….[NaOH/\( \text{NH}_4\text{OH} \)] can be used.
Answer: NaOH

Question. Oxides and hydroxide of certain metals i.e………… (iron/zinc/copper/aluminium/magnesium/lead] are amphoteric and react with…………… [acids/alkali/acids and alkalis].
Answer: zinc, aluminium and lead; acids and alkalis

Question. Complete the following equations:
1. \( \text{MgCl}_2 + \text{NH}_4\text{OH} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots \)
2. \( \text{Zn} + \text{NaOH} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots \)
3. \( \text{ZnO} + \text{NaOH} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots \)
4. \( \text{Al(OH)}_3 + \text{KOH} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots \)
5. \( \text{Zn(OH)}_2 + \text{NaOH (excess)} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots \)
6. \( \text{Pb(NO}_3)_2 + \text{NH}_4\text{OH} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots \)
7. \( \text{Al}_2\text{O}_3 + \text{KOH} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots \)
8. \( \text{FeCl}_3 + \text{NaOH} \rightarrow \dots\dots\dots\dots + \dots\dots\dots\dots \)
Answer:
(i) \( \text{MgCl}_2 + 2\text{NH}_4\text{OH} \rightarrow 2\text{NH}_4\text{Cl} + \text{Mg(OH)}_2\downarrow \)
(ii) \( \text{Zn} + 2\text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + \text{H}_2 \) [sodium zincate]
(iii) \( \text{ZnO} + 2\text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + \text{H}_2\text{O} \) [sodium zincate]
(iv) \( \text{Al(OH)}_3 + \text{KOH} \rightarrow \text{KAlO}_2 + 2\text{H}_2\text{O} \) [potassium aluminate]
(v) \( \text{Zn(OH)}_2 + 2\text{NaOH (excess)} \rightarrow \text{Na}_2\text{ZnO}_2 + 2\text{H}_2\text{O} \) [sodium zincate]
(vi) \( \text{Pb(NO}_3)_2 + 2\text{NH}_4\text{OH} \rightarrow 2\text{NH}_4\text{NO}_3 + \text{Pb(OH)}_2\downarrow \)
(vii) \( \text{Al}_2\text{O}_3 + 2\text{KOH} \rightarrow 2\text{KAlO}_2 + \text{H}_2\text{O} \) [potassium aluminate]
(viii) \( \text{FeCl}_3 + 3\text{NaOH} \rightarrow 3\text{NaCl} + \text{Fe(OH)}_3\downarrow \)