Acids Bases and Salts ICSE Class-10 Concise Chemistry Selina Solutions

Acids Bases and Salts ICSE Class-10 Concise Chemistry Selina Solutions Chapter-3. We Provide Step by Step Answer of Intext -1, Exercise-3 A ,Exercise-3 B  Exercise-3 C , Miscellaneous  and Previous Year Questions of Exercise-3 Acids Bases and Salts ICSE Class-10 . Visit official Website CISCE  for detail information about ICSE Board Class-10.

Acids Bases and Salts ICSE Class-10 Concise Chemistry Selina Solutions Chapter-3

Board	ICSE
Publications	Selina Publishers PVT LTD
Subject	Concise Chemistry
Class	10th
writer	Dr SP Singh
Chapter-3	Acid, Bases and Salt
Topics	Intext -1 & 2 and Exercise-3A, 3B and 3C Questions
Edition	2021-2022

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-: Select Topics :-

Intext 1, 

Intext 2

Exercise 3-A, 

Exercise 3-B  

Exercise 3-C, 

Miscellaneous

Previous Year Questions

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Acids Bases and Salts Selina Concise Chemistry Solution Chapter 3 Intext 1

 Page-42

Question 1

(a) What do you understand by the term, acid?

(b) Name the positive ion formed when an acid is dissolved in water.

(c) Draw the structure of this ion.

Answer 1

(a) Acids are defined as compounds which contain one or more hydrogen atoms, and when dissolved in water, they produce hydronium ions (H₃O⁺), the only positively charged ions.

(b) Hydronium ion

(c) H₃O⁺

Question 2  

Write the ionisation reaction of sulphuric acid showing the formation of hydronium ion.

Answer 2

H2SO4 + H₂O ⇌ H₃O⁺ + HSO4-

HSO4- + H₂O ⇌ H₃O⁺ + SO4-2

Question 3 :

Water is never added to acid in order to dilute it. Why?

Answer 3 :

If water is added to a concentrated acid, the heat generated causes the mixture to splash out and cause severe burns. Thus, water is never added to acid in order to dilute it.

Question 4 :

Define the term ‘basicity’ of an acid. Give the basicity of: nitric acid, sulphuric acid, phosphoric acid?

Answer 4 : 

Basicity: The basicity of an acid is defined as the number of hydronium ions (H₃O⁺) that can be produced by the ionization of one molecule of that acid in aqueous solution.

• The basicity of following compounds are:
• Nitric acid: Basicity= 1
• Sulphuric acid: Basicity=2
• Phosphoric acid: Basicity=3

Question 5 : 

Give two examples of each of the following:

(a) Oxy-acid

(b) Hydracid

(c) Tribasic acid

(d) Dibasic acid

Answer 5

(a) Oxyacids: – HNO₃, H₂SO₄

(b) Hydracid:- HCl, HBr

(c) Tribasic acid:- H₃PO₄, H₃PO₃

(d) Dibasic acid: – H₂SO₄ , H₂CO₃

Question 6

Name the

(a) acidic anhydride of the following acids:

(i) Sulphurous acid

(ii) Nitric acid

(iii) Phosphoric acid

(iv) Carbonic acid

(b) Acids present in vinegar, grapes and lemon?

Answer 6

(a) The anhydride of following acids are:

(i) Sulphurous acid: SO₂

(ii) Nitric acid: N₂O₅

(iii) Phosphoric acid: P₂O₅

(iv) Carbonic acid: CO₂

(b) Acids present in following are:

Vinegar: Acetic acid

Grapes: Tartaric acid and Malic acid

Lemon: Citric acid

Question 7

What do you understand by the statement ‘acetic acid is a mono basic’ acid?

Answer 7

Acetic acid is a mono basic acid which on ionization in water produce one hydronium ion per molecule of the acid.

Question 8

Give a balanced equation for (i) reaction of nitrogen dioxide with water (ii) Preparation of non-volatile acid from a volatile acid.

Answer 8

(i) 2NO_2(g) + H₂O_(l)→ HNO_2(aq) + HNO₃

(ii) H₂S₂O₇ + H₂O  → 2 H₂SO₄

Question 9

What do you understand by the strength of acid? On which factors does the strength of an acid depend?

Answer 9

The strength of an acid is the extent to which the acid ionizes or dissociates in water.

The strength of an acid depends on the degree of ionization and concentration of hydronium ions [H₃O⁺] produced by that acid in aqueous solution.

Question 10

Explain the following:

(a)Carbonic acid gives an acid salt but hydrochloric acid does not. Explain.

(b) Dil. HCl acid is stronger than highly concentrated acetic acid. Explain.

(c) H₃PO₃ is not a tribasic acid.

(d) Lead carbonate does not react with dilute HCl.

(e) Nitrogen dioxide is a double acid anhydride.

Answer 10

(a)

Carbonic acid is a dibasic acid with two replaceable hydrogen ions; therefore it forms one acid salt or one normal salt.

Hydrochloric acid is a monobasic acid with one replaceable hydrogen ion and so forms only one normal salt.

(b)

 Strength of an acid is the measure of concentration of hydronium ions it produces in its aqueous solution. Dil. HCl produces high concentration of hydronium ion compared to that of concentrated acetic acid. Thus, dil. HCl is stronger acid than highly concentrated acetic acid.

(c)

 H₃PO₃ is not a tribasic acid because in oxyacids of phosphorus, hydrogen atoms which are attached to oxygen atoms are replaceable. Hydrogen atoms directly bonded to phosphorus atoms are not replaceable.

(d)

 The salt produced is insoluble in the solution so the reaction does not proceed. Hence, we do not expect lead carbonate to react with hydrochloric acid.

(e)

 NO₂ is called double acid anhydride because two acids – nitrous acid and nitric acid – are formed when it reacts with water.

2NO₂ + H₂O → HNO₂ + HNO₃

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Page-43

Question 11

How is an acid prepared from a (a) non-metal (b) salt? Give an equation for each.

Answer 11

 (a) Acids are prepared from non-metals by their oxidation. For example :

Sulphur or phosphorus is oxidized by conc. Nitric acid to form sulphuric acid or phosphoric acid.

(b) Acids are prepared from salt by the displacement reaction. For example :

Nitric acid is prepared by using H₂SO₄ and sodium chloride.

Question 12

Give an equation to show how the following are made from their corresponding anhydrides.

(a) Sulphurous acid

(b) Phosphoric acid

(c) Carbonic acid

(d) Sulphuric acid

Answer 12

(a) SO₂ +H₂O H₂SO₃

(b) P₂O₅ +3H₂O 2H₃PO₄

(c) CO₂ + H₂O H₂CO₃

(d)

Question 13

Name an acid used:

(a) To flavor and preserve food

(b) In a drink

(c) To remove ink spots

(d) As an eyewash

Answer 13

(a) Citric acid

(b) Carbonic acid

(c) Oxalic acid

(d) Boric acid

Question 14

Give the reaction of acids with

(a) Chlorides

(b) Nitrates

State the conditions under which they react.

Answer 14

(a) Chlorides react with concentrated sulphuric acid on warming to liberate hydrogen chloride.

(b) Nitrates when heated with conc. sulphuric acid produce more volatile nitric acid.

Both chlorides and nitrates do not react with dilute acids; they react with concentrated acids.

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 Acids Bases and Salts Concise Chemistry Selina Solutions for ICSE Class 10 Exe-3 A

Page-47

Question 1

What do you understand by an alkali? Give two examples of :

(a) Strong alkalis

(b) Weak alkalis

Answer 1

An alkali is a basic hydroxide which when dissolved in water produces hydroxyl ions (OH^–) as the only negatively charged ions.

(a) Strong alkalis: Sodium hydroxide , Potassium hydroxide

(b) Weak alkalis: Calcium hydroxide , Ammonium hydroxide

Question 2

What is the difference between :

(a) An alkali and a base

(b) The chemical nature of an aqueous solution of HCl and an aqueous solution of NH₃

Answer 2

(a) An alkali and a base:

(i) Alkalis are soluble in water whereas bases may be or may not be soluble in water.

(ii) All alkalis are bases but all bases are not alkalis.

(b) The chemical nature of an aqueous solution of HCl and an aqueous solution of NH₃

(i) The aqueoussolution of HCl is acidic in nature. It can turn blue litmus to red.

(ii) The aqueoussolution of NH₃ is basic in nature. It can turn red litmus to blue.

Question 3

Name the ions furnished by

(a) bases in solution

(b) an acid

Answer 3

(a) Hydroxyl ion (OH^–)

(b) H⁺

Question 4

Give one example in each case:

(a) A basic oxide which is soluble in water,

(b) A hydroxide which is highly soluble in water,

(c) A basic oxide which is insoluble in water,

(d) A hydroxide which is insoluble in water,

(e) A weak mineral acid,

(f) A base which is not an alkali,

(g) An oxide which is a base,

(h) A hydrogen containing compound which is not an acid,

(i) A base which does not contain a metal ion.

Answer 4

(a) Barium oxide

(b) Sodium hydroxide

(c) Manganese oxide

(d) Cupper hydroxide

(e) Carbonic acid

(f) Ferric hydroxide

(g) Copper oxide

(h) Ammonia

(i) Ammonium hydroxide

Question 5

You have been provided with three test tubes. One of them contains distilled water and the other two have an acidic solution and a basic solution respectively. If you are given red litmus paper, how will you identify the contents of each test tube?

Answer 5

The test tube containing distilled water does not affect the red litmus paper.

The test tube containing acidic solution does not change the red litmus paper.

But the test tube containing basic solution turns red litmus paper blue.

Question 6

HCl, HNO₃, C₂H₅OH, C₆H₁₂O₆ all contain H atoms but only HCl and HNO₃ show acidic character. Why?

Answer 6

It is because HCl and HNO₃ ionize in aqueous solution whereas ethanol and glucose do not ionize in aqueous solution.

Question 7

(a) Dry HCl gas does not change the colour of dry litmus paper. Why?

(b) lsPbO₂ a base or not? Comment.

(c) Do basic solutions also have H⁺_(aq)? Explain why they are basic by taking an example ?

Answer 7

(a) Dry HCl gas does not contain any hydrogen ions in it, so it does not show acidic behaviour. Hence, dry HCl gas does not change the colour of dry litmus paper.

(b) Lead oxide is a metallic oxide which reacts with hydrochloric acid to produce lead chloride and water, but it is excluded from the class of bases, because chlorine is also produced.

PbO₂ + 4HCl → PbCl₂ + Cl₂ + 2H₂O

Thus, lead oxide is not a base.

(c) Yes, basic solutions have H⁺ions, but the concentration of OH^– ions is more than the H⁺ ions which makes the solution basic in nature.

Question 8

How would you obtain:

(a) A base from other base

(b) An alkali from a base

(c) Salt from another salt?

Answer 8

(a) We can obtain a base from another base by double decomposition. The aqueous solution of salts with base precipitates the respective metallic hydroxide.

FeCl₃ +3NaOH Fe(OH)₃ +3NaCl

(b) An alkali from a base

_(c) Salt from another salt

Question 9

Write balanced equations to satisfy each statement.

(a) Acid + Active metal    Salt + Hydrogen

(b) Acid + base       Salt + Water

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Page-48

(c) Acid + Carbonate or bicarbonate             Salt + Water + carbon dioxide

(d) Acid + sulphite or bisulphit        e salt + water + sulphur dioxide

(e) Acid + Sulphide             Salt + hydrogen sulphide

Answer 9

(a) Mg +2HCl      MgCl₂ + H₂

(b) HCl + NaOH     NaCl + H₂O

(c) CaCO₃ +2HCl    CaCl₂ +H₂O + CO₂

(d) CaSO₃ + 2HCl    CaCl₂ + H₂O+ SO₂

(e) ZnS + 2HCl    ZnCl₂ + H₂S

Question 10

The skin has and needs natural oils. Why is it advisable to wear gloves while working with strong alkalis?

Answer 10

As we know that alkalis react with oil to form soap. As our skin contains oil so when we touch strong alkalis, a reaction takes place and soapy solution is formed. Hence we should wear gloves.

Question 11

Complete the table:

Indicator	Neutral	Acidic	Alkaline
Litmus Phenol-phthalein	Purple Colourless

Answer 11

Indicator	Neutral	Acidic	Alkaline
Litmus Phenol-phthalein	Purple Colourless	Blue to red Colourless	Red to blue Pink

Question 12

What do you understand by pH value? Two solutions X and Y have pH values of 4 and 10, respectively. Which one of these two will give a pink colour with phenolphthalein indicator?

Answer 12 

pH represents the strength of acids and alkalis expressed in terms of hydrogen ion concentration.

The solution with pH value 10 will give pink colour with phenolphthalein indicator.

Question 13

You are supplied with five solutions : A , B , C , D and E with pH values as follows:

A =1.8 , B=7 , C=8.5 , D=13 and E=5

Classify these solutions as neutral, slightly or strongly acidic and slightly or strongly alkaline.

Which solution would be most likely to liberate hydrogen with:

(a) Magnesium powder

(b) Powered zinc metal. Give a word equation for each reaction.

Answer 13

A = Strongly acidic

B= neutral

C=Weakly alkaline

D= Strongly alkaline

E= Weakly acidic

(a) Solution A (acidic solution) + MgH₂ + Mg salt

(b) Solution A (acidic solution) + ZnH₂ + Zn salt

Question 14

Distinguish between :

(a) A common acid-base indicator and a universal indicator

(b) The acidity of bases and basicity of acids

(c) Acid and alkali (other than indicators)

Answer 14

(a) A common acid-base indicator and a universal indicator:

An acid-base indicator like litmus tells us only whether a given substance is an acid or a base. The universal indicator gives an idea as to how acidic or basic a substance is universal indicator gives different colours with solutions of different pH values.

(b) The acidity of bases and basicity of acids

The acidity of bases: The number of hydroxyl ions which can be produced per molecule of the base in aqueous solution.

Basicity of acid: The basicity of an acid is defined as the number of hydronium ions that can be produced by the ionization of one molecule of that acid in aqueous solution.

(c) Acid and alkali:

An acid is that substance which gives H⁺ ions when dissolved in water.

An alkali is that substance which gives OH^– ions when dissolved in water.

Question 15

What should be added to

(a) Increase the pH value

(b) Decrease the pH value of a neutral solution?

Answer 15

(a) Alkali

(b) Acid

Question 16

How does tooth enamel get damaged? What should be done to prevent it?

Answer 16 

Substances like chocolates and sweets are degraded by bacteria present in our mouth. When the pH falls to 5.5 tooth decay starts. Tooth enamel is the hardest substance in our body and it gets corroded. The saliva produced by salivary glands is slightly alkaline, it helps to increase the pH, to some extent, but toothpaste which contains basic substance is used to neutralize excess acid in the mouth.

Question 17

When you use universal indicator, you see that solutions of different acids produce different colours. Indeed, solution of the same acid with different concentrations will also give different colours. Why?

Answer 17

A universal indicator is a mixture of dyes which identify a gradual change of various colours over a wide range of pH, depending on the strength of the acid. When we use a universal indicator, we see solutions of different acids produce different colours. Indeed, solutions of the same acid with different concentration give different colours.

The more acidic solutions turn universal indicator bright red. A less acidic solution will only turn it orange-yellow. Colour differences can also be observed in case of vinegar which is less acidic and battery acid which is more acidic.

Question 18

(a) A solution has a pH of 7. Explain how you would

(i) increase its pH

(ii) decrease its pH

(b) If a solution changes thecolour of litmus from red to blue, what can you say about its pH?

(c) What can you say about the pH of a solution that liberates carbon dioxide from sodium carbonate?

Answer 18

(a)

(i) The pH can be increased by adding a basic solution.

(ii) The pH can be increased by adding an acidic solution.

(b) The solution is basic in nature and the pH value will be more than 7.

(c) Less than 7

Question 19

Solution P has a pH of 13, solution Q has a pH of 6 and solution R has a pH of 2.

Which solution

(a) will liberate ammonia from ammonium sulphate on heating?

(b) is a strong acid?

(c) contains molecules as well as ions?

Answer 19

(a) Solution P

(b) Solution R

(c) Solution Q

Question-20

M is an element in the form of a powder. M burns in oxygen and the product obtained is soluble in water. The solution is tested with litmus. Write down only the word which will correctly complete each of the following sentences.

(i) If M is a metal, then the litmus will turn _____________.
(ii) If M is a non-metal, then the litmus will turn ______________.
(iii) If M is a reactive metal, then _________________ will be evolved when M reacts with dilute sulphuric acid.
(iv) If M is a metal, it will form ______________ oxide, which will form ____________ solution with water.
(v) If M is a non-metal, it will not conduct electricity in the form of __________.

Answer-20

(i) If M is a metal, then the litmus will turn blue.
(ii) If M is a non-metal, then the litmus will turn red.
(iii) If M is a reactive metal, then hydrogen gas will be evolved when M reacts with dilute sulphuric acid.
(iv) If M is a metal, it will form basic oxide, which will form alkaline solution with water.
(v) If M is a non-metal, it will not conduct electricity in the form of graphite.

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Concise Selina Chemistry Solution Acids Bases and Salts Chapter 3 for ICSE  Class-10

 Excercise – 3(B)

Page-55

Question 1

Define the following and give two examples in each case:

(a) a normal salt, (b) an acid salt, (c) a mixed salt.

Answer 1

(a) A normal salt:

 Normal salts are the salts formed by the complete replacement of the ionizable hydrogen atoms of an acid by a metallic or an ammonium ion.

(b) An acidic salt:

 Acid salts are formed by the partial replacement of the ionizable hydrogen atoms of a polybasic acid by a metal or an ammonium ion.

(c) A mixed salt:

Mixed salts are those salts that contain more than one basic or acid radical.

Examples:

(a) A Normal salt: Na₂SO₄ , NaCl

(b) An acid salt: NaHSO₄ , Na₂HPO₄

(c) A mixed salt: NaKCO₃ , CaOCl₂

Question 2

Answer the following questions related to salts and their preparations:

(a) What is a salt?

(b) What kind of salt is prepared by precipitation?

(c) Name a salt prepared by the direct combination. Write an equation for the reaction that takes place in preparing the salt you have named.

(d) Name the procedure used to prepare a sodium salt such as sodium sulphate.

Answer 2

(a) Salt is a compound formed by the partial or total replacement of the ionizable hydrogen atoms of an acid by a metallic ion or an ammonium ion.

(b) An insoluble salt can be prepared by precipitation.

(c) A salt prepared by direct combination is Iron(III) chloride.

Reaction:

2Fe +3Cl₂ 2FeCl₃

(d) By neutralizing sodium carbonate or sodium hydroxide with dilute sulphuric acid:

Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂

2 NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O

Question-3

Explain the following method with example

(a) Direct combination

(b) Displacement method

(c) Double Decomposition (precipitation)

(d) neutralisation of insoluble salt

(e) Neutralisation of alkali (titration)

Answer-3

(a) Direct combination

A reaction in which two or more substances combine. together to form a single substance is called a combination reaction

Fe + S —–FeS

(b) Displacement method

Reactions in which the more reactive element displaces the less reactive element from its compound are called displacement reactions.

For example:

Zinc displaces copper in copper sulphate to form zinc sulphate.

Zn_(s)   +     CuSO_{4 (aq)}           →               ZnSO_{4 (aq)}   +       Cu_(s)

Zinc      Copper sulphate                      Zinc sulphate        Copper

(c) Double Decomposition (precipitation)

Reactions in which ions of the reactants exchange places to form two new compounds, are called double displacement reactions.

For example:

Sodium hydroxide reacts with hydrochloric acid to form sodium chloride and water.

NaOH_(aq)      +         HCl_(aq)        →     NaCl_(aq)         +        H₂O_(l)

(d) neutralisation of insoluble salt

1. An insoluble salt can be prepared by a precipitation method through a double decomposition reaction.
2. In this method two aqueous solutions of two different soluble salts are mixed together to form the insoluble salt. The insoluble salt is formed as a precipitate and can be obtained by filtration.
3. (a) The first solution must have a soluble salt which contains the cation of the insoluble salt.
   (b) The second solution must have a soluble salt which contains the anion of the insoluble salt.

(e) Neutralisation of alkali (titration)

The concentration of an acid or alkali can be calculated by carrying out an experiment called a titration.

Materials

The apparatus needed includes:

• a pipette to accurately measure a certain volume of acid or alkali
• a pipette filler to use the pipette safely
• a conical flask to contain the liquid from the pipette
• a burette to add small, measured volumes of one reactant to the other reactant in the conical flask

Apparatus needed to carry out a titration

Method

This is an outline method for carrying out a titration in which an acid is added to alkali.

1. Use the pipette and pipette filler to add 25 cm³ of alkali to a clean conical flask.
2. Add a few drops of indicator and put the conical flask on a white tile.
3. Fill the burette with acid and note the starting volume.
4. Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
5. Stop adding the acid when the end-point is reached (the appropriate colour change in the indicator happens). Note the final volume reading.
6. Repeat steps 1 to 5 until you get concordant readings (see explanation below).

The same method works for adding an alkali to an acid – just swap around the liquids that go into the conical flask and burette.

Question 4

how would you prepare :

(a) Copper sulphate crystals from mixture of charcoal and black copper oxide,

(b) Zinc sulphate crystals from Zinc dust (powered Zinc and Zinc oxide)

(c) sodium hydrogen carbonate crystals

(d) Calcium sulphate from calcium carbonate

Answer 4

(a) Copper sulphate crystals from a mixture of charcoal and black copper oxide:

The carbon in the charcoal reduces the black copper oxide to reddish-brown copper. The lid must not be removed until the crucible is cool or the hot copper will be re-oxidized by air.

Take dilute sulphuric acid in a beaker and heat it on wire gauze. Add cupric oxide in small quantities at a time, with stirring till no more of it dissolves and the excess compound settles to the bottom.

Filter it hot and collect the filtrate in a china dish. Evaporate the filtrate by heating to the point of crystallization and then allow it to cool and collect the crystals of copper sulphate pentahydrate.

Reaction: CuO + H₂SO₄ CuSO₄ + H₂O

CuSO₄ + 5H₂O CuSO_4. 5H₂O

(b) Zinc sulphate crystals from Zinc dust:

Take dilute sulphuric acid in a beaker and heat it on wire gauze. Add some granulated zinc pieces with constant stirring. Add till the Zinc settles at the base of the beaker. Effervescences take place because of the liberation of hydrogen gas. When effervescence stops, it indicates that all the acid has been used up. The excess of zinc is filtered off. Collect the solution in a china dish and evaporate the solution to get crystals. Filter, wash them with water and dry them between the folds of paper. The white needle crystals are of hydrated Zinc sulphate.

Reaction: Zn + H₂SO₄ ZnSO₄ + H₂

ZnSO₄ +7 H₂O ZnSO_4. 7 H₂O

(c) Lead sulphate from metallic lead:

Metallic lead is converted to lead oxide by oxidation. Then lead sulphate is prepared from insoluble lead oxide, by first converting it into soluble lead nitrate. Then the lead nitrate solution is treated with sulphuric acid to obtain white ppt. of Lead sulphate.

Reaction:

PbO +2HNO₃ Pb(NO₃)₂ + H₂O

Pb(NO₃)₂ + H₂SO₄ PbSO₄ + 2HNO₃

(d)Sodium hydrogen carbonate crystals:

Dissolve 5 grams of anhydrous sodium carbonate in about 25 ml of distilled water in a flask. Cool the solution by keeping the flask in a freezing mixture. Pass carbon dioxide gas in the solution. Crystals of sodium bicarbonate will precipitate out after some time. Filter the crystals and dry it in folds of filter paper.

Reaction: Na₂CO₃ + CO₂ + H₂O 2NaHCO₃

Question 5

The following is the list of methods for the preparation of salts.

A-Direct combination of two elements.

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B-reaction of dilute acid with a metal.

C-reaction of dilute acid with an insoluble base.

D-Titration of dilute acid with a solution of soluble base.

E- reaction of two solutions of salts to form a precipitate.

Choose from the above list A to E , the best method of preparing the following salts by giving a suitable equation in each case:

1. Anhydrous ferric chloride,
2. Lead chloride,
3. Sodium sulphate,
4. Copper sulphate.

Answer 5 

1. Anhydrous ferric chloride: -A (Direct combination of two elements)

2Fe + 3Cl₂ 2FeCl₃

2.Lead chloride: -E (Reaction of two solutions of salts to form a precipitate)

Pb(NO₃)₂ +2HCl PbCl₂ +2HNO₃

3.Sodium sulphate: – D( Titration of dilute acid with a solution of soluble base)

2NaOH + H₂SO₄ Na₂SO₄ +2H₂O

4. Copper sulphate:- C (reaction of dilute acid with an insoluble base)

Cu(OH)₂ +H₂SO₄ CuSO₄ + 2H₂O

Question 6

Name:

(a) A chloride which is insoluble in cold water but dissolves in hot water,

(b) A chloride which is insoluble,

(c) Two sulphates which are insoluble,

(d) A basic salt,

(e) An acidic salt,

(f) A mixed salt,

(g) A complex salt,

(h) A double salt,

(i) a salts whose solubility increases with temperature,

(j) A salt whose solubility decreases with temperature.

Answer 6

(a) Lead chloride

(b) Silver chloride

(c) Barium sulphate and lead sulphate

(d) Basic lead chloride

(e) Sodium hydrogen sulphate

(f) Sodium potassium carbonate

(g) Sodium argentocyanide

(h) Potash alum

(i) Potassium bromide and potassium chloride

(j) Calcium sulphate

Question 7

Fill in the blanks with suitable words:

An acid is a compound which when dissolved in water forms hydronium ions as the only …………… ions. A base is a compound which is soluble in water and contains …………….. ions. A base reacts with an acid to form a …………….. and water only. This type of reaction is known as …………….

Answer 7

An acid is a compound which when dissolved in water forms hydronium ions as the only positively charged ions. A base is a compound which is soluble in water and contains hydroxide ions. A base reacts with an acid to form a salt and water only. This type of reaction is known as neutralisation.

Question 8

What would you observe when:

(a) Blue litmus is introduced into a solution of hydrogen chloride gas.

(b) Red litmus paper is introduced into a solution of ammonia in water

(c) Red litmus paper is introduced in Caustic soda solution?

Answer 8

(a) Blue litmus will turn into red which will indicate the solution to be acidic.

(b) No change will be observed.

(c) Red litmus will turn into blue will indicate the solution to be basic.

Question 9

Explain why:

(a) It is necessary to find out the ratio of reactants required in the preparation of sodium sulphate.

(b) Fused calcium chloride is used in the preparation of FeCl₃.

(c) Anhydrous FeCl₃ cannot be prepared by heating hydrated iron (III) chloride.

Answer 9

(a) Since sodium hydroxide and sulphuric acid are both soluble, an excess of either of them cannot be removed by filtration. Therefore it is necessary to find out on small scale, the ratio of solutions of the two reactants.

(b) As iron chloride is highly deliquescent, so it is kept dry with the help of fused calcium chloride.

(c) On heating the hydrate, HCl acid is released and basic salt (FeOCl) or ferric oxide remains. Hence, anhydrous ferric chloride cannot be prepared by heating the hydrate.

Question 10

Give the preparation of the salt shown in the left column by matching with the methods given in the right column. Write a balanced equation for each preparation.

Salt Method of preparation

Zinc Sulphate Precipitation

Ferrous sulphide Oxidation

Barium Sulphate Displacement

Ferric sulphate Neutralisation

Sodium sulphate Synthesis

Answer 10

Zinc Sulphate – Displacement

Ferrous sulphide – synthesis

Barium sulphate – Precipitation

Ferric Sulphate- Oxidation

Sodium sulphate – Neutralisation

Question 11

(a) Give the pH value of pure water. Does it change if common salt is added to it?

(b) Classify the following solutions as acids, bases or salts. Ammonium hydroxide, barium chloride, sodium chloride, sodium hydroxide, H₂SO₄ and HNO₃

Answer 11

(a) pH of pure water is 7 at 25^oC. No, the pH does not change when common salt is added.

(b) Acids: H₂SO₄ and HNO₃

Bases: Ammonium hydroxide and sodium hydroxide.

Salts: Barium chloride and sodium chloride.

Question 12

Define the term neutralization.

(a) Give a reaction, mentioning clearly acid and base used in the reaction.

(b) If one mole of a strong acid reacts with one mole of a strong base, the heat produced is always same. Why?

Answer 12

Neutralization is the process by which H⁺ ions of an acid react completely with the [OH]^– ions of a base to give salt and water only.

(a)

(b) Neutralization is simply a reaction between H⁺ ions given by strong acid and OH^– ions given by strong base. In case of all strong acids and strong bases, the number of H⁺ and OH^– ions produced by one mole of a strong acid or strong base is always same. Hence the heat of neutralization of a strong acid with strong base is always same.

Question 13

Write the balanced equation for the preparation of the following salts in the laboratory:

(a) A soluble sulphate by the action of an acid on an insoluble base,

(b) An insoluble salt by the action of an acid on another salt,

(c) An insoluble base by the action of a soluble base on a soluble salt

(d) A soluble sulphate by the action of an acid on a metal.

Answer 13

_(a)

_(b)

(c)

_(d)

Question 14

You are provided with the following chemicals:

NaOH,Na₂CO₃,H₂O,Zn(OH)₂,CO₂,HCl,Fe,H₂SO₄,Cl₂,Zn

Using suitable chemicals from the given list only, state briefly how you would prepare:

(a) Iron(III) chloride,

(b) Sodium sulphate,

(c) Sodium zincate,

(d) Iron(II) sulphate,

(e) Sodium chloride.

Answer 14

(a) Iron (III) Chloride: Iron chloride is formed by direct combination of elements.

_(b) Sodium sulphate: By neutralization of caustic soda with dilute sulphuric acid

_(c) Sodium zincate: By the action of metals with alkalis

_(d) Iron (II) sulphate: Iron sulphate is prepared by the action of dilute acid on an active metal.

_(e) Sodium chloride: By the neutralization reaction of strong acid with strong base

Question 15

For each of the salt: A, B, C and D, suggest a suitable method of its preparation.

(a) A is a sodium salt.

(b) B is an insoluble salt.

(c) C is a soluble salt of copper.

(d) D is a soluble salt of zinc.

Answer 15

(a) By neutralisation:

NaOH + HCl → NaCl + H₂O

(b) By precipitation:

Pb(NO₃)₂ + 2NaCl → PbCl₂ + 2NaNO₃

(c) CuCO₃+ H₂SO₄→ CuSO₄ + H₂O + CO₂

(d) Simple displacement:

Zn + H₂SO₄→ ZnSO₄ + H₂

Question 16

Choosing only substances from the list given in the box below, write equations for the reactions which you would use in the laboratory to obtain:

(a) Sodium sulphate

(b) Copper sulphate

(c) Iron(II)sulphate

(d) Zinc carbonate

Dilute sulphuric acid	Copper	Copper carbonate
	Iron	Sodium carbonate
	Sodium
	Zinc

Answer 16 

 (a) Na₂CO₃+ H₂SO₄ (dil) → Na₂SO₄ + H₂O + CO₂

(b) CuCO₃+ H₂SO₄ (dil) → CuSO₄ + H₂O + CO₂

(c) Fe + H₂SO₄(dil) → FeSO₄ + H₂

(d) Zn + H₂SO₄(dil) → ZnSO₄ + H₂

(e)  ZnSO₄ + Na₂CO₃ → ZnCO₃ + Na₂SO₄

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Page-57

Question 17

From the formula listed below, choose one, in each case, corresponding to the salt having the given description: AgCl, CuCO₃, CuSO₄.5H₂O, KNO₃, NaCl, NaHSO₄, Pb(NO₃)₂, ZnCO₃, ZnSO₄.7H₂O.

(a) an acid salt

(b) an insoluble chloride

(c) on treating with concentrated sulphuric acid, this salt changes from blue to white

(d) on heating, this salt changes from green to black

(e) this salt gives nitrogen dioxide on heating

Answer 17

(a) NaHSO₄

(b) AgCl

(c) CuSO₄.5H₂O

(d) CuCO₃

(e) Pb(NO₃)₂

Question 18

(a) Ca(H₂PO₄)₂is an example of a compound called _______ (acid salt/basic salt/normal salt).

(b) Write the balanced equation for the reaction of: A named acid and a named alkali.

Answer 18

(a) acid salt

(b) NaOH+ HCl → NaCl + H₂O

Question 19

State the terms defined by the following sentences:

(a) A soluble base.

(b) The insoluble solid formed when two solutions are mixed together.

(c) An acidic solution in which there is only partial ionisation of the solute molecules.

Solution 19

(a) Alkali

(b) Precipitate

(c) Weak acid

Question 20

Which of the following methods, A, B, C, D or E is generally used for preparing the chlorides listed below from (i) to (v). Answer by writing down the chloride and the letter pertaining to the corresponding method. Each letter is to be used only once.

A Action of an acid on a metal

B Action of an acid on an oxide or carbonate

C Direct combination

D Neutralisation of an alkali by an acid

E Precipitation (double decomposition)

(i) Copper (II) chloride

(ii) Iron (II) chloride

(iii). Iron (III) chloride

(iv) Lead (II) chloride

(v) Sodium chloride

Answer 20 

(i) Copper (II) chloride – B

(ii) Iron (II) chloride – A

(iii). Iron (III) chloride – C

(iv) Lead (II) chloride – E

(v) Sodium chloride – D

Question-21

Choose the most appropriate answer from ( SO₂ , SiO₂ , Al₂O3 , CO , MgO , Na₂O )
(a) A covalent oxide of a metalloid.
(b) An oxide which when dissolved in water form acid .
(c) A basic oxide
(d) An amphoteric oxide

Answer-21

a) Silicon is a metalloid. The covalent oxide is SiO_​2
b) Acidic oxide – gives acid with water – SO₂
SO₂ + H₂O —-> H₂SO₃
c) Basic oxide – gives base with water – Na₂O
Na₂O + H₂O —–> 2 NaOH
d) An amphoteric oxide – Shows both acidic and basic property
Al₂O₃

Question 22

Complete the following table:

Reactants	Products	Method
Soluble base + Acid (dil)	Salt + water	Neutralisation Titration
Metal + Non-metal	Salt (soluble/insoluble)	……………
Insoluble base +	Salt (soluble) + water	…………….
Active metal + Acid (dil)	………… + …………	…………….
Soluble salt solution (A) +	Precipitated salt +	…………….
Soluble salt solution (B)	Soluble salt	…………….
Carbonate/ bicarbonate + Acid (dil)	Salt + ………. + …………	Decomposition of carbonate
Chlorides/nitrates + Acid (conc)	…………. + …………	Decomposition of chlorides and nitrates

Answer 22

Reactants	Products	Method
Soluble base + Acid (dil)	Salt + water	Neutralisation Titration
Metal + Non-metal	Salt (soluble/insoluble)	Direct Combination
Insoluble base +	Salt (soluble) + water	…………….
Active metal + Acid (dil)	Salt + Hydrogen	Displacement
Soluble salt solution (A) + Soluble salt solution (B)	Precipitated salt + Soluble salt	Precipitation
Carbonate /bicarbonate + Acid (dil)	Salt + Water+ Carbon dioxide	Decomposition of carbonate
Chlorides/nitrates + Acid (conc)	Acid salt + HCl/HNO3	Decomposition of chlorides and nitrates

 

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ICSE Concise Chemistry Selina Solutions Chapter-3 Acids, Bases and Salts

Exercise – 3(C)

Page-60

Question 1 : 

What do you understand by water of crystallisation? Give four substances which contain water of crystallisation and write their common names.

Answer 1 :

It is the amount of water molecules which enter into loose chemical combination with one molecule of the substance on crystallization from its aqueous solution.

Common name	Chemical name	Formula
Washing soda	Sodium carbonate dehydrate	Na2CO3.10H2O
Epsom salt	Magnesium sulphate heptahydrate	MgSO4. 7H2O
Potash alum	Hydrated potassium aluminium sulphate	K2SO4.Al(SO4)3.24H2O
Gypsum	Hydrated calcium sulphate	CaSO4.2H2O

Question 2

(a) Define efflorescence. Give examples.

(b) Define deliquescence. Give examples.

Answer 2

(a) Crystalline hydrated salts which on exposure to the atmosphere lose their water of crystallisation partly or completely and change into a powder. This phenomenon is called efflorescent and the salts are called efflorescent.

Examples: CuSO₄.5H₂O, MgSO₄.7H₂O, Na₂CO₃.10H₂O

(b) Water-soluble salts which on exposure to the atmosphere absorb moisture from the atmosphere and dissolve in the same and change into a solution. The phenomenon is called deliquescence and the salts are called deliquescent.

Examples: CaCl₂, MgCl₂, ZnCl₂

Question 3

Answer the questions below relating your answers only to salts in the following list: Sodium chloride, anhydrous calcium chloride, copper sulphate-5-water?

(a) What name is given to the water in the compound copper sulphate-5-water?

(b) If copper sulphate-5-water is heated, anhydrous copper sulphate is formed. What is its colour?

(c) By what means, other than healing, could you dehydrate copper sulphate-5-water and obtain anhydrous copper sulphate?

(d) Which one of the salts in the given list is deliquescent?

Answer-3

(a)Water of crystallization

(b)White

(c) By heating with any dehydrating agent

(d )Anhydrous calcium chloride

Question-4

State your observation when the following are exposed to the atmosphere.

(a) Washing soda crystals

(b) Iron (III) chloride salts

Answer-4

(a) When washing soda (Na₂CO₃.10H₂O) is exposed to air, it loses 9 molecules of water to form a monohydrate.

(b) It absorbs moisture from the atmosphere and becomes moist and ultimately dissolves in the absorbed water, forming a saturated solution.

Question-5

Give reason for the following:

a )Sodium hydrogen sulphate is not an acid but it dissolves in water to give hydrogen ions, according to the equation
NaHSO₄ ⇆ H⁺ + Na⁺ + SO₄^2-

b)

Desiccating agents are used to absorb moisture. Anhydrous calcium chloride (CaCl₂) has the capacity of absorbing moisture as it is hygroscopic in nature. So, it is used in a desiccator.

Question 6

Explain clearly how conc. H₂SO₄ is used as a dehydrating as well as a drying agent.

Answer 6

Conc. sulphuric acid is hygroscopic in nature and can remove moisture from other substances; therefore, it is used as a drying agent.

It is also used as a dehydrating agent because it has a strong affinity for water and thus absorbs water quickly from compounds.

Question 7

Distinguish between drying and dehydrating agent.

Answer 7

Drying agents	Dehydrating agents
remove moisture from other substances.	remove chemically combined elements of water in the ratio of 2:1 (hydrogen : oxygen) from a compound.
They are used to dry gases like chlorine, sulphur dioxide and hydrogen chloride. are also used in dessicators to keep substances dry.	prepare substances such as carbon monoxide and sugar charcoal.
represent a physical change.	represent a chemical change.

Question 8

State whether a sample of each of the following would increase or decrease in mass if exposed to air.

(a) Solid NaOH

(b) Solid CaCl₂

(c) Solid Na₂CO₃.10H₂O

(d) Conc. sulphuric acid

(e) Iron (III) chloride

Answer 8

(a) Increase

(b) Increase

(c) Decrease

(d) Increase

(e) Increase

Question 9

(a) Why does common salt get wet during the rainy season?

(b) How can this impurity be removed?

(c) Name a substance which changes the blue colour of copper sulphate crystals to white.

(d) Name two crystalline substances which do not contain water of crystallisation.

Answer 9

(a) Table salt turns moist and ultimately forms a solution on exposure to air especially during the rainy season. Although pure sodium chloride is not deliquescent, the commercial version of the salt contains impurities (such as magnesium chloride) which are deliquescent substances.

(b) The impurity can be removed by passing a current of dry hydrogen chloride gas through a saturated solution of the affected salt. Pure sodium chloride is produced as a precipitate which can be recovered by filtering and washing first with a little water and finally with alcohol.

(c) Conc. sulphuric acid

(d) Common salt and sugar

Question 10

Name the salt which on hydrolysis forms

(a) Acidic

(b) Basic acid

(c) Neutral solution. Give a balanced equation for each reaction.

Answer 10

(a) Iron chloride(FeCl₃)

FeCl₃ + 3H₂O → 3HCl + Fe(OH)₃

(b) Ammonium acetate (CH₃COONH₄)

CH₃COONH₄ +H₂O → CH₃COOH + NH₄OH

(c) Sodium chloride

NaCl_(s) + H₂O → Na⁺_(aq)  OH^–_(aq) + H₂O

Question 11

State the change noticed when blue litmus and red litmus are introduced in the following solutions:

(a) Na₂CO₃ solution

(b) NaCl solution

(c) NH₄NO₃

(d) MgCl₂ Solution

Answer 11

(a) Na₂CO₃ solution: This solution is alkaline in nature; hence, red litmus changes to blue.

(b) NaCl solution: There is no change in the colour of the litmus paper because this solution is neutral.

(c) NH₄NO₃: This solution is alkaline in nature; hence, red litmus changes to blue.

(d) MgCl₂: It is slightly acidic and neutral; hence, there is no change in the litmus paper.

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Selina Solution Acids Bases and Salts Chapter 3

Excercise – Misc

Page-61

Question 1 :

Write the balanced equations for the preparation of the following compounds (as major product) starting from iron and using only one other substance:

(a) Iron (II) chloride

(b) Iron (III) chloride

(c) Iron (II) sulphate

(d) Iron (II) sulphide

Answer 1

(a) Fe + 2HCl (dil) FeCl₂ + H₂

(bi) 2Fe (heated) + 3Cl₂ (dry)  2FeCl₃

(c) Fe + H₂SO₄ (dil)  FeSO₄ + H₂

(d) Fe + S  FeS

Question 2

Write a balanced reaction for the following conversions (A, B, C, D) (2015)

Answer 2

A = HCl

B = Na₂CO₃

C = HNO₃

D = NaOH

A: Fe + 2HCl → FeCl₂ + H₂

B: FeCl₂ + Zn→ ZnCl₂ + Fe

Fe + H₂CO₃ → FeCO₃ + H₂↑

C: FeCO₃ + 2HNO₃ → Fe (NO₃)₂ + H₂O + CO₂

D: Fe(NO₃)₂ + 2NaOH → Fe(OH)₂ + 2NaNO₃

Question 3

Answer 3

(i) A salt containing a metal ion surrounded by other ions or molecules.

(ii) A base which is soluble in water.

(b) Making use only of substances chosen from those given below:

Dilute sulphuric acid Sodium Carbonate

Zinc Sodium sulphite

Lead Calcium carbonate

Give equations for the reactions by which you could obtain :

(i) Hydrogen

(ii) Sulphur dioxide

(iii) Carbon dioxide

(iv) Zinc carbonate (two steps required)

Answer 4

(i) Complex salts

(ii) Alkali

(i)

(ii)

(iii)

(iv)

 Previous Year Questions of Exe-3 Acids Bases and Salts for Selina Concise Chemistry

Page-61

Question 2009

(a) The acid which contains four hydrogen atoms

(i) Formic

(ii) Sulphuric

(iii)  Nitric

(iv) Acetic acid

(b) A black-coloured solid which on reaction with dilute sulphuric acid forms a blue-coloured solution is

(i) Carbon

(ii) Manganese [IV] oxide

(iii) Lead [II] oxide

(iv) Copper [II] oxide

(c) Solution A is a strong acid, B is a weak acid and C is a strong alkali.

(i) Which solution contains solute molecules in addition to water molecules?

(ii) Which solution will give a gelatinous white precipitate with zinc sulphate solution? The precipitate disappears when an excess of the solution is added.

(iii)  Give an example of a weak alkali.

(d) Write the equations[s] for the reaction[s] to prepare lead sulphate from lead carbonate.

(e) Define the following term -Neutralisation.

(f) The diagram given below is to prepare iron [III] chloride in the laboratory:

(i) What is substance B?

(ii) What is the purpose of B?

(iii)  Why is iron [III] chloride to be stored in a closed container?

(iv) Write the equation for the reaction between iron and chlorine.

Answer 2009 

(a) (iv) Acetic acid

(b) (iv) Copper (II) oxide

(c)

(i) Solution B

(ii) Solution C

(iii) Ammonium hydroxide solution

(d)

(e) A neutralisation reaction is when an acid and a base react to form water and a salt, and involves the combination of H⁺ ions and OH^– ions to generate water.

(f)

(i) B is an anhydrous calcium chloride.

(ii) B absorbs moisture from the receiver.

(iii)  Because iron (III) chloride is highly deliquescent and it absorbs moisture from the surrounding air to form a saturated solution.

(iv)

Question 2010 

(a) Select the correct answer from A, B, C, D and E:

(A) Nitroso iron [II] sulphate

(B) Iron [III] chloride

(C) Chromium sulphate

(D) Lead chloride

(E) Sodium chloride

(i)A deliquescent compound

(ii) A compound soluble in hot water but insoluble in cold water

(iii) A compound which in the aqueous solution state is neutral in nature.

(b) Select the correct answer from A, B, C and D:

(i) A weak organic acid is

A. Formic acid

B. Sulphuric acid

C. Nitric acid

D. Hydrochloric acid

(ii) A complex salt is

A. Zinc sulphate

B. Sodium hydrogen sulphate

C. Iron [ammonium sulphate]

D Tetrammine copper [II] sulphate

(c) Give equations for the following conversions A to E:

(d) For the preparation of the following salts, give a balanced equation in each case.

(i) Copper [II] sulphate from copper [II] oxide

(ii) Iron [III] chloride from the metal iron

(iii). Potassium sulphate from KOH solution

(iv) Lead [II] chloride from lead carbonate [give two equations]

Answer 2010 

(a)

 A (ii)

B (iv)

C (v)

(b)

 (i) A

(ii) D

(c)

(i)

(ii)

(iii)

(iv)

(d)

(i)

(ii)

(iii)

(iv)

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Page-62

Question 2011 

(a) Write the balanced chemical equation: Lead nitrate solution is added to sodium chloride solution.

(b) State what happens to crystals or washing soda when exposed to air. Name the phenomenon exhibited.

(c) Name the method used for the preparation of the following salts from the list given below:

(i) Sodium nitrate

(ii) Iron (III) chloride

(iii)Lead chloride

(iv) Zinc sulphate

(v) Sodium hydrogen sulphate

list:

A. Simple displacement

B. Neutralisation

C Decomposition by acid

D Double decomposition

E Direct synthesis

Answer 2011

(a) Pb(NO₃)₂+ 2NaCl → PbCl₂ + 2NaNO₃

(b) When crystals of washing soda are exposed to air, it loses its water of crystallisation and the phenomenon is known as efflorescence.

(c)

(i) (B) Neutralisation

(ii) (E) Direct synthesis

(iii)(D) Double decomposition

(iv) (A) Simple displacement

(v) (C) Decomposition by acid

Question 2012 

(a) Match the following :

Column A	Column B
A. Acid salt	A. Ferrous ammonium   sulphate
B. Double salt	B. Contains only ions
C. Ammonium hydroxide solution	C. Sodium hydrogen sulphate
D. Dilute hydrochloric acid	D. Contains only molecules
E. Carbon tetrachloride molecules	E. Contains ions and molecules

Answer 2012

(a) 1→C

2→A

3→E

4→B

5→D

Question 2013 

(a)

 Select the word/s given which are required to correctly complete the blanks – [ammonia, ammonium carbonate, carbon dioxide, hydrogen, hydronium, hydroxide, precipitate, salt, water]

(i) A solution M turns blue litmus red, so it must contain (1) …….. ions; another solution turns red litmus blue, and hence, must contain (2) ………. ions.

(ii) When solution M and 0 are mixed together, the products will be (3) …….. and (4) ………….

(iii). If a piece of magnesium was put into a solution M, (5) ………….. gas would be evolved.

(b)

 Give a suitable chemical term for:

(i) A salt formed by incomplete neutralisation of an acid by a base.

(ii) A definite number of water molecules bound to some salts.

(iii). The process in which a substance absorbs moisture from the atmospheric air to become moist, and ultimately dissolves in the absorbed water.

(c)

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:

(i) sodium sulphate

(ii) zinc carbonate

(iii). copper [II] sulphate

(iv) iron [II] sulphate

Answer 2013 

(a)

(i) Hydronium

(ii) Hydroxide

(iii). Salt

(iv) Water

(v) Hydrogen

(b)

(i) Acidic salt

(ii) Water of crystallisation

(iii). Deliquescence

(c)

Chemical equations:

(i) Sodium sulphate:

2Na + H₂SO₄ (dil.) → Na₂SO₄ + H₂↑

(ii) Zinc carbonate:

Zn(NO₃)₂ + CuCO₃→ ZnCO₃ + Cu(NO₃)₂

(iii). Copper (II) sulphate:

CuCO₃ + H₂SO₄ (dil.) → CuSO₄ + H₂O + CO₂

(iv) Iron (II) sulphate:

Fe + H₂SO₄ (dil.) → FeSO₄ + H₂↑

Question 2014

(a) Fill in the blank from the choices given: The basicity of acetic acid is …………… [3, 1, 4].

(b) Draw the structure of the stable positive ion formed when an acid dissolves in water.

(c) State the inference drawn from the observation:

Salt S is prepared by reacting dilute sulphuric acid

with copper oxide. Identify S.

(d) Give balanced chemical equations for the preparation of the following salts:

(i) Lead sulphate – from lead carbonate

(ii) Sodium sulphate – using dilute sulphuric acid

(iii) Copper chloride – using copper carbonate

Answer 2014 

(a) 1

(b) The stable positive ion formed when an acid dissolves in water ishydronium ion. The structure of hydronium ion (H₃O⁺) is as follows:

(c) Salt S is prepared by reacting dilute sulphuric acid with copper oxide. Hence, salt S is copper sulphate.

(d) i Lead sulphate from lead carbonate

(ii) Sodium sulphate using dilute sulphuric acid Dilute sulphuric acid neutralises bases (oxides and hydroxides) to form salts and water.

(iii). Copper chloride using copper carbonate

Question 2015 

(a) 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:

(i) A deliquescent salt (ii) An insoluble chloride

(b) From Na₂O, SO₂, SiO₂,Al₂O₃,MgO, CO, select an oxide which dissolves in water forming an acid.

Answer 2015

(a)

A deliquescent salt	An insoluble chloride
MgCl2	AgCl

(b) SO₂ is an acidic oxide which dissolves in water forming an acid.

Question 2016

Match the salts given in Column I with their method of preparation given in Column II :

Column I	Column II
(i) Pb(NO3)2 from PbO (ii) MgCl2 from Mg (iii) FeCl3 from Fe (iv) NaNO3 from NaOH (v) ZnCO3 from ZnSO4	A) Simple displacement B) Titration C) Neutralization D) Precipitation E) Combination

Answer 2016

Column I	Column II
Pb(NO3)2 from PbO	Precipitation
MgCl2 from Mg	Simple displacement
FeCl3 from Fe	Combination
NaNO3 from NaOH	Neutralisation
ZnCO3 from ZnSO4	Titration

–: End of Chapter-3 Acid Base And Salt Selina Chemistry Solutions :-

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