SELINA Solutions for Class 9 Chemistry Chapter 1 - The Language of Chemistry

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Chapter 1 - The Language of Chemistry Exercise Ex. 1(C)

Question 1

 

Fill in the blanks:

  1. Dalton used symbol _____ for oxygen _____ for hydrogen.
  2. Symbol represents _____ atom(s) of an element.
  3. Symbolic expression for a molecule is called _____.  .
  4. Sodium chloride has two radicals. Sodium is a _____ radical while chloride is _____ radical.
  5. Valency of carbon in CH4 is _____ , in C2H6 _____, in C2H4 ___ and in C2H2 is ____.
  6. Valency of Iron in FeCl2 is _____  and in FeCl3 it is ____ .
  7. Formula of iron (ill) carbonate is _____ .

 

 

Solution 1
  1. Dalton used symbol [O] for oxygen,[H] for hydrogen.
  2. Symbol represents gram atom(s) of an element.
  3. Symbolic expression for a molecule is called molecular formula.
  4. Sodium chloride has two radicals. Sodium is a basic radical, while chloride is an acid radical.
  5. Valency of carbon in CH4 is 4, in C2H64, in C2H44 and in C2H2 is 4.
  6. Valency of iron in FeCl2 is 2 and in FeCl3 it is 3.
  7. Formula of iron (III) carbonate is Fe2[CO3]3.

 

Question 2

 

Complete the following table.

 

 

 Acid Radicals 

 Selina Solutions Icse Class 9 Chemistry Chapter - The Language Of Chemistry

Basic Radicals

Chloride

Nitrate

Sulphate 

Carbonate

Hydroxide

Phosphate

Magnesium

MgCl2

Mg(NO3)2

MgSO4

MgCO3

Mg(OH)2

 Mg3(PO4)2

Sodium

 

 

 

 

 

 

Zinc

 

 

 

 

 

 

Silver

 

 

 

 

 

 

Ammonium

 

 

 

 

 

 

Calcium

 

 

 

 

 

 

Iron (II)

 

 

 

 

 

 

Potassium

 

 

 

 

 

 

 

 

Solution 2

 

 

 

 Acid Radicals 

 

 

 Selina Solutions Icse Class 9 Chemistry Chapter - The Language Of Chemistry

Basic Radicals

Chloride

Nitrate

Sulphate 

Carbonate

Hydroxide

Phosphate

Magnesium

MgCl2

Mg(NO3)2

MgSO4

MgCO3

Mg(OH)2

 Mg3(PO4)2

Sodium

NaCl 

NaNO3

Na2SO4

Na2CO3

NaOH 

Na3PO4

Zinc

ZnCl2

Zn(NO3)2

Zn(SO4)2

ZnCO3

Zn(OH)2

Zn3(PO4)2

Silver

AgCl 

AgNO3

Ag2SO4

AgCO3

AgOH 

Ag3PO4

Ammonium

NH4Cl

NH4NO3

(NH4)2SO4

(NH4)2CO3

NH4OH

(NH4)3PO4

Calcium

CaCl2

CaCO3

CaSO4

CaCO3

Ca(OH)2

Ca3(PO4)2

Iron (II)

FeCl2

Fe(NO3)2

FeSO4

FeCO3

Fe(OH)2

Fe3(PO4)2

Potassium

KCl 

KNO3

K2SO4

K2CO3

KOH

K3PO4

 

 

Question 3

 

Sodium chloride reacts with silver nitrate to produce silver chloride and sodium nitrate

  1. Write the equation.
  2. Check whether it is balanced, if not balance it.
  3. Find the weights of reactants and products.
  4. State the law which this equation satisfies. 
Solution 3

 

a. NaCl + AgNO3 → NaNO3 + AgCl

 

b. It is a balanced equation.

 

c. Weights of reactants: NaCl - 58.44, AgNO3 - 169.87 

    Weights of products: NaNO3 - 84.99, AgCl - 143.32

    NaCl + AgNO3  NaNO3  + AgCl

    (23+35.5) + (108+14+48) → (23+14+48) + (108+35.5)

    58.5 + 170  85 + 143.5

    228.5 g  228.5 g

 

d. Law of conservation of mass: Matter is neither created nor destroyed in the course of a chemical reaction.

Question 4(a)

 

What information does the following chemical equation convey?

Zn + H2SO4 → ZnSO4+ H2

 

Solution 4(a)

 

This equation conveys the following information:

 

  1. The actual result of a chemical change.
  2. Substances take part in a reaction, and substances are formed as a result of the reaction.
  3. Here, one molecule of zinc and one molecule of sulphuric acid react to give one molecule of zinc sulphate and one molecule of hydrogen.
  4. Composition of respective molecules, i.e. one molecule of sulphuric acid contains two atoms of hydrogen, one atom of sulphur and four atoms of oxygen.
  5. Relative molecular masses of different substances, i.e. molecular mass of

Zn = 65

H2SO4 = (2+32+64) = 98

ZnSO4 = (65+32+64) = 161  

H2 = 2

  1. 22.4 litres of hydrogen are formed at STP.

 

Question 4(b)

What information do the following chemical equations convey? Mg + 2HCl → MgCl2+ H2

Solution 4(b)

This equation conveys the following information:

 

  1. Magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas.
  2. 24 g of magnesium reacts with 2(1 + 35.5) = 73 g of hydrochloric acid to produce (24 + 71), i.e. 95 g of magnesium chloride.
  3. Hydrogen produced at STP is 22.4 litres. 
Question 5(a)

What are polyatomic ions? Give two examples.

Solution 5(a)

A polyatomic ion is a charged ion composed of two or more covalently bounded atoms. Examples: Carbonate (CO32-) and sulphate (SO42-)

Question 5(b)

Name the fundamental law that is involved in every equation.

 

Solution 5(b)

Fundamental laws which are involved in every equation:

  1. A chemical equation consists of formulae of reactants connected by a plus sign (+) and arrow () followed by the formulae of products connected by the plus sign (+).
  2. The sign of an arrow () is to read 'to form'. It also shows the direction in which the reaction is predominant.

The fundamental law followed by every equation is 'Law of Conservation of Mass'.

Question 6(a)

What is the valency of :

fluorine in CaF2 

Solution 6(a)

Valency of fluorine in CaF2 is -1. 

Question 6(b)

What is the valency of :

sulphur in SF6

Solution 6(b)

Valency of sulphur in SF6 is -6.

Question 6(c)

What is the valency of :

phosphorus in PH3 

Solution 6(c)

Valency of phosphorus in PH3 is +3.

Question 6(d)

What is the valency of :

carbon in CH4

Solution 6(d)

Valency of carbon in CH4 is +4.

Question 6(e)

What is the valency of :

nitrogen in the following compounds:

(i) N2O3 (ii) N2O5 (iii) NO2 (iv) NO

Solution 6(e)

Valency of nitrogen in the given compounds:

  1. N2O3  = N is +3 
  2. N2O5 = N is +5
  3. NO2 = N is +4
  4. NO = N is +2

 

Question 7

Why should an equation be balanced? Explain with the help of a simple equation.

Solution 7

According to the law of conservation of mass, 'matter can neither be created nor can it be destroyed'. This is possible only if the total number of atoms on the reactants side is equal to the total number of atoms on the products side. Thus, a chemical reaction should always be balanced.

e.g.  KNO3 → KNO2 + O2

In this equation, the number of atoms on both sides is not the same, and the equation is not balanced.

The balanced form of this equation is

2KNO3 → 2KNO2 + O2

 

Question 8(a)

Write the balanced chemical equations of the following reactions. sodium hydroxide + sulphuric acid → sodium sulphate + water

Solution 8(a)

2NaOH + H2SO4 → Na2SO4 + 2H2O

Question 8(b)

Write the balanced chemical equations of the following reactions. potassium bicarbonate + sulphuric acid → potassium sulphate + carbon dioxide + water

Solution 8(b)

2KHCO3 + H2SO4 → K2SO4 + 2CO2 + 2H2O

Question 8(c)

Write the balanced chemical equations of the following reactions. iron + sulphuric acid → ferrous sulphate + hydrogen.

Solution 8(c)

Fe + H2SO4 → FeSO4 + H2

Question 8(d)

Write the balanced chemical equations of the following reactions.

chlorine + sulphur dioxide + water →  sulphuric acid + hydrogen chloride

Solution 8(d)

Cl2 + SO2 + 2H2O → H2SO4 + 2HCl

Question 8(e)

Write the balanced chemical equations of the following reactions.

silver nitrate → silver + nitrogen dioxide + oxygen

Solution 8(e)

2AgNO3 → 2Ag + 2NO2 + O2

Question 8(f)

Write the balanced chemical equations of the following reactions.

copper + nitric acid → copper nitrate + nitric oxide + water

Solution 8(f)

3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O

Question 8(g)

Write the balanced chemical equations of the following reactions.

ammonia + oxygen → nitric oxide + water

Solution 8(g)

 Selina Solutions Icse Class 9 Chemistry Chapter - The Language Of Chemistry 

Question 8(h)

Write the balanced chemical equations of the following reactions.

barium chloride + sulphuric acid → barium sulphate + hydrochloric acid

Solution 8(h)

BaCl2 + H2SO4 → BaSO4 + 2HCl

Question 8(i)

Write the balanced chemical equations of the following reactions.

zinc sulphide + oxygen → zinc oxide + sulphur dioxide

Solution 8(i)

2ZnS + 3O2 → 2ZnO + 2SO2

Question 8(j)

Write the balanced chemical equations of the following reactions.

aluminium carbide + water → aluminium hydroxide + methane

Solution 8(j)

Al4C3 + 12H2O → 4Al(OH)3 + 3CH4

Question 8(k)

Write the balanced chemical equations of the following reactions.

iron pyrites(FeS2) + oxygen  ferric oxide + sulphur dioxide

Solution 8(k)

 4FeS2 + 11O2 → 2Fe2O3 + 8SO2

Question 8(l)

Write the balanced chemical equations of the following reactions.

potassium permanganate + hydrochloric acid potassium chloride + manganese chloride + chlorine + water

Solution 8(l)

2KMnO4 + HCl → 2KCl + 2MnCl2 + 5Cl2 + 8H2O

Question 8(m)

Write the balanced chemical equations of the following reactions.

aluminium sulphate + sodium hydroxide → sodium sulphate + sodium meta aluminate + water.

Solution 8(m)

Al2(SO4)3 + 8NaOH → 3Na2SO4 + 2NaAlO2 + 4H2O

Question 8(n)

Write the balanced chemical equations of the following reactions.

aluminium + sodium hydroxide + water → sodium meta aluminate + hydrogen

Solution 8(n)

2Al + 2NaOH + 2H2O → 2NaAlO2 + 3H2

Question 8(o)

Write the balanced chemical equations of the following reactions.

potassium dichromate + sulphuric acid → potassium sulphate + chromium sulphate + water + oxygen.

Solution 8(o)

2K2Cr2O7 + 8H2SO4 → 2K2SO4 + 2Cr2(SO4)3 + 8H2O + 3O2

Question 8(p)

Write the balanced chemical equations of the following reactions.

potassium dichromate + hydrochloric acid Potassium chloride + chromium chloride + water + chlorine

Solution 8(p)

K2Cr2O7 + 14HCl → 2KCl + 2CrCl3 + 7H2O + 3Cl2

Question 8(q)

Write the balanced chemical equations of the following reactions.

sulphur + nitric acid → sulphuric acid + nitrogen dioxide + water.

Solution 8(q)

S + HNO3 → H2SO4 + NO2 + H2O 

Question 8(r)

Write the balanced chemical equations of the following reactions.

sodium chloride + manganese dioxide + sulphuric acid → sodium hydrogen sulphate  + manganese sulphate + water + chlorine.

Solution 8(r)

2NaCl + MnO2 + 3H2SO4 → 2NaHSO4 + MnSO4 + 2H2O + Cl2

Question 9(b)(i)

Calculate the molecular mass of the following:

CuSO4·5H2O

Given atomic mass of Cu = 63·5, H = 1, O = 16, C=12, N = 14, Mg = 24, S = 32

Solution 9(b)(i)

Molecular mass of CuSO4.5H2O

63.5 + 32 + (4 × 16) + (10 × 1) + (5 × 16)

= 63.5 + 32 + 64 + 10 + 80

= 249.5

Question 9(a)

Define atomic mass unit.

Solution 9(a)

Atomic mass unit (amu) is equal to one-twelfth the mass of an atom of carbon-12 (atomic mass of carbon taken as 12).

Question 9(b)(ii)

Calculate the molecular mass of the following:

(NH4)2CO3  

Given atomic mass of Cu = 63·5, H = 1, O= 16, C = 12, N = 14, Mg = 24, S = 32

 

Solution 9(b)(ii)

Molecular mass of (NH4)2CO3

= (2 × 14) + (8 × 1) + 12 + (3 × 16)

= 28 + 8 + 12 + 48

= 96

Question 9(b)(iii)

 Calculate the molecular mass of the following:

(NH2)2CO   

Given atomic mass of Cu = 63·5, H = 1, O= 16, C = 12, N = 14, Mg = 24, S = 32

Solution 9(b)(iii)

Molecular mass of (NH2)2CO

= (14 × 2) + (4 × 1) + 12 + 16

= 28 + 4 + 12 + 16

= 60 

Question 9(b)(iv)

Calculate the molecular mass of the following:

Mg3N2

Given atomic mass of Cu = 63·5, H = 1, O = 16, C = 12, N = 14, Mg = 24, S = 32

Solution 9(b)(iv)

Molecular mass of Mg3N2

= (3 × 24) + (2 × 14)

= 72 + 28

= 100

Question 10(a)

Choose the correct answer from the options given below.

Modern atomic symbols are based on the method proposed by

 i. Bohr  

 ii. Dalton

 iii. Berzelius

 iv. Alchemist 

Solution 10(a)

iii. Berzelius

Question 10(b)

Choose the correct answer from the options given below.

The number of carbon atoms in a hydrogen carbonate radical is

  1. One
  2. Two
  3. Three
  4. Four 
Solution 10(b)

i. One

Question 10(c)

Choose the correct answer from the options given below.

The formula of iron (III) sulphate is

 i. Fe3SO4 

 ii. Fe(SO4)3

 iii. Fe2(SO4)3

 iv. FeSO4 

Solution 10(c)

iii. Fe2(SO4)3

Question 10(d)

Choose the correct answer from the options given below.

In water, the hydrogen-to-oxygen mass ratio is  

  1. 1: 8  
  2. 1: 16
  3. 1: 32  
  4. 1: 64  
Solution 10(d)

i. 1:8

 

Question 10(e)

Choose the correct answer from the options given below.

The formula of sodium carbonate is Na2CO3 and that of calcium hydrogen carbonate is

 i. CaHCO3

 ii. Ca(HCO3)2

 iii. Ca2HCO3

 iv. Ca(HCO3)3

Solution 10(e)

ii. Ca(HCO3)2

Chapter 1 - The Language of Chemistry Exercise Ex. 1(B)

Question 1

What is a chemical equation? Why it is necessary to balance it?

Solution 1

A chemical equation is the symbolic representation of a chemical reaction using the symbols and formulae of the substances involved in the reaction.

A chemical equation needs to be balanced because a chemical reaction is just a rearrangement of atoms.

Atoms themselves are neither created nor destroyed during the course of a chemical reaction.

The chemical equation needs to be balanced to follow the law of conservation of mass.

Question 2

State the information conveyed by the following equation:

Zn(s) + 2HCl(aq)  ZnCl2(aq)  + H2

Solution 2

A solid metal zinc reacts with hydrochloric acid in the aqueous state to produce zinc chloride in the aqueous state and hydrogen gas.

Question 3

What is the limitation of the reaction given in question 2?

Solution 3
  • The chemical equation given in question 2 does not give the time taken for the completion of the reaction.
  • Also, it does not give information about whether heat is absorbed or evolved during the reaction.
Question 4

Write the chemical equations for the following word equations and balance them.

  1. Carbon   + Oxygen Carbon dioxide
  2. Nitrogen + Oxygen Nitrogen monoxide
  3. Calcium + Nitrogen Calcium nitride
  4. Calcium oxide + Carbon dioxide Calcium carbonate
  5. Magnesium + Sulphuric acid Magnesium sulphate + Hydrogen
  6. Sodium reacts with water to form sodium hydroxide and hydrogen
Solution 4
  1. C + O2 CO2
  2. N2 + O2 2NO
  3. 3Ca + N2 Ca3N2
  4. CaO + CO2 CaCO3
  5. Mg + H2SO4 MgSO4 + H2 
  6. Na + H2O NaOH + H2
Question 5

Balance the following equations:

a. Fe + H2O → Fe3O4 + H2

b. Ca + N2 → Ca3N2

c. Zn + KOH → K2ZnO2 + H2

d. Fe2O3 + CO → Fe + CO2

e. PbO + NH3Pb + H2O + N2

f. Pb3O4PbO + O2

g. PbS + O2PbO + SO2

h. S + H2SO4 → SO2 + H2O

i. S + HNO3 → H2SO4 + NO2 + H2O

j. MnO2 + HCl → MnCl2 + H2O + Cl2

k. C + H2SO4 → CO2 + H2O + SO2

l. KOH + Cl2KCl + KClO + H2O

m. NO2 +H2O → HNO2 + HNO3

n. Pb3O4 + HCl → PbCl2 + H2O + Cl2

o. H2O + Cl2HCl + O2

p. NaHCO3 → Na2CO3 + H2O + CO2

q. HNO3 + H2S → NO2 + H2O + S

r. P + HNO3 → NO2 + H2O + H3PO4

s. Zn + HNO3  → Zn(NO3)2 + H2O + NO2

 

Solution 5

Balanced chemical equations:

 

  1. 3Fe + 4H2O → Fe3O4 + 4H2
  2. 3Ca + N2 → Ca3N2
  3. Zn + 2KOH → K2ZnO2 + H2
  4. Fe2O3 + 3CO → 2Fe + 3CO2
  5. 3PbO + 2NH3 → 3Pb + 3H2O + N2
  6. 2Pb3O4 → 6PbO + O2
  7. 2PbS + 3O2 → 2PbO + 2SO2
  8. S + 2H2SO4 → 3SO2 + 2H2O
  9. S + 6HNO3 → H2SO4 + 6NO2 + 2H2O
  10. MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
  11. C + 2H2SO4 → CO2 + H2O + SO2
  12. 2KOH + Cl2KCl + KClO + H2O
  13. 2NO2 + H2O → HNO2 + HNO3
  14. Pb3O4 + 8HCl → 3PbCl2 + 4H2O + Cl2
  15. 2H2O + 2Cl2 → 4HCl + O2
  16. 2NaHCO3 → Na2CO3 + H2O + CO2
  17. 2HNO3 + H2S → 2NO2 + 2H2O + S
  18. P + 5HNO3 → 5NO2 + H2O + H3PO4 
  19. Zn + 4HNO3  → Zn(NO3)2 + 2H2O + 2NO2

Chapter 1 - The Language of Chemistry Exercise Ex. 1(A)

Question 1

What is a symbol? What information does it convey?

Solution 1

A symbol is the short form which stands for the atom of a specific element or the abbreviations used for the names of elements.

  1. It represents a specific element.
  2. It represents one atom of an element.
  3. A symbol represents how many atoms are present in its one gram (gm) atom.
  4. It represents the number of times an atom is heavier than one atomic mass unit (amu) taken as a standard.

 

Question 2

Why is the symbol S for sulphur, but Na for sodium and Si for silicon?

 

Solution 2

In most cases, the first letter of the name of the element is taken as the symbol for that element and written in capitals (e.g. for sulphur, we use the symbol S). In cases where the first letter has already been adopted, we use a symbol derived from the Latin name (e.g. for sodium/Natrium, we use the symbol Na). In some cases, we use the initial letter in capital together with a small letter from its name (e.g. for silicon, we use the symbol Si). 

Question 3

Write the full form of IUPAC. Name the elements represented by the following symbols:

Au, Pb, Sn, Hg

Solution 3

The full form of IUPAC is International Union of Pure and Applied Chemistry.

Names of the elements:

Au - Gold 

Pb - Lead

Sn - Tin

Hg - Mercury

Question 4

If the symbol for Cobalt, Co, were written as CO, what would be wrong with it?

Solution 4

Co stands for Cobalt. If we write CO, then it would mean that it is a compound containing two non-metal ions, i.e. carbon and oxygen, which forms carbon monoxide gas. 

Question 5(d)

2H2 

Solution 5(d)

2H2 stands for two molecules of hydrogen.

Question 6

What is meant by atomicity? Name the diatomic element.

 

Solution 6

The number of atoms of an element that join together to form a molecule of that element is known as its atomicity.

Diatomic molecules: H2, O2, N2, Cl2

Question 7(a)

Explain the terms 'valency' and 'variable valency'.

Solution 7(a)
  1. Valency of Na is +1 because it can lose one electron.
  2. Valency of O is -2 because it can accept two electrons.

 

Variable valency: It is the combining capacity of an element in which the metal loses more electrons from a shell next to a valence shell in addition to electrons of the valence shell.

Question 7(b)

How are the elements with variable valency named? Explain with an example.

Solution 7(b)

If an element exhibits two different positive valencies, then  

 

 i. for the lower valency, use the suffix -OUS at the end of the name of the metal

 ii. for the higher valency, use the suffix -IC at the end of the name of the metal.

 

Example:

 

Element

Lower valency

Higher valency

Ferrum (Iron)

Ferrous (Fe2+)

Ferric (Fe3+)

 

Question 8

Give the formula and valency of:

  1. aluminate ………………… .
  2. chromate ………….…….. .
  3. aluminium ………………. .
  4. cupric  ………………… . 
Solution 8

 

 

 

Name

Formula

Valency 

a.

Aluminate 

AlO2

-2

b.

Chromate

CrO4

-2

c.

Aluminium 

Al

+3

d.

Cupric

Cu

+2

 

 

Question 9.b

What is the significance of formula?

Solution 9.b

Significance of the molecular formula:

  • It represents both molecule and molecular mass of the compound.
  • It represents the respective number of different atoms present in one molecule of the compound.
  • It represents the ratios of the respective masses of the elements present in the compound.
Question 10(a)

What do you understand by the following terms?

Acid radical 

Solution 10(a)

Acid radical: The electronegative or negatively charged radical is called an acid radical.  

Examples: Cl-, O2- 

Question 10(b)

What do you understand by the following terms?

Basic radical

Solution 10(b)

Basic radical: The electropositive or positively charged radical is called a basic radical.  

Examples: K+, Na+ 

Question 11

Select the basic and acidic radicals in the following compounds.

  1. MgSO4 
  2. (NH4)2SO4
  3. Al2(SO4)3
  4. ZnCO3
  5. Mg(OH)2 
Solution 11

 

 

 

Acidic radical

Basic radical

  1. MgSO4 

SO4-

Mg+

  1. (NH4)2SO4 

SO4-

NH4+

  1. Al2(SO4)3 

SO4-

Al3+

  1. ZnCO3 

CO3-

Zn2+

  1. Mg(OH)2 

OH-

Mg2+

 

 

Question 12

Write chemical formula of the sulphate of Aluminium, Ammonium and Zinc.

Solution 12

Valencies of aluminium, ammonium and zinc are 3, 1 and 2, respectively.

The valency of sulphate is 2.

Hence, chemical formulae of the sulphates of aluminium, ammonium and zinc are Al2(SO4)3, (NH4)2SO4 and ZnSO4.

Question 13

The valency of an element A is 3 and that of element B is 2. Write the formula of the compound formed by the combination of A and B.

Solution 13

 

Formula of the compound = A2B3

 

Question 14

Match the following:

 

Compound

Formula

  1. Boric acid

 i. NaOH 

  1. Phosphoric acid

 ii. SiO2

  1. Nitrous acid

 iii. Na2CO3

  1. Nitric acid

 iv. KOH

  1. Sulphurous acid

 v. CaCO3

  1. Sulphuric acid

 vi. NaHCO3

  1. Hydrochloric acid

 vii. H2S

  1. Silica (sand)

 viii. H2O

i. Caustic soda

(sodium hydroxide)

 ix. PH3

  1. Caustic potash (potassium hydroxide)

 x. CH4

k. Washing soda

(sodium carbonate)

 xi. NH3

l. Baking soda

(sodium bicarbonate)

 xii. HCl 

m. Lime stone.

(calcium carbonate)

 xiii. H2SO3

  1. Water

 xiv. HNO3

  1. Hydrogen sulphide

 xv. HNO2

  1. Ammonia

 xvi. H3BO3

  1. Phosphine 

 xvii. H3PO4

  1. Methane

 xviii. H2SO4

  

Solution 14

 

 

Compound

Formula (Ans)

  1. Boric acid

xvi. H3BO3

  1. Phosphoric acid

xvii. H3PO4

  1. Nitrous acid

xv. HNO2

  1. Nitric acid

xiv. HNO3

  1. Sulphurous acid

xiii. H2SO3

  1. Sulphuric acid

xviii. H2SO4

  1. Hydrochloric acid

xii. HCl

  1. Silica (sand)

ii. SiO2

  Caustic soda

     (sodium hydroxide)

i. NaOH

Caustic potash (potassium hydroxide)

iv. KOH

 Washing soda

(sodium carbonate)

iii. Na2CO3

 Baking soda

(sodium bicarbonate)

vi. NaHCO3

 Lime stone

(calcium carbonate)

v. CaCO3

  1. Water

viii. H2O

  1. Hydrogen sulphide

vii. H2S

  1. Ammonia

xi. NH3

  1. Phosphine 

ix. PH3

  1. Methane

x. CH4

 

 

Question 15

Write the basic radicals and acidic radicals of the following

and then write the chemical formulae of these compounds.

  1. Barium sulphate  
  2. Bismuth nitrate
  3. Calcium bromide  
  4. Ferrous sulphide
  5. Chromium sulphate
  6. Calcium silicate
  7. Potassium ferrocyanide
  8. Stannic oxide
  9. Magnesium phosphate
  10. Sodium zincate
  11. Stannic phosphate
  12. Sodium thiosulphate
  13. Potassium manganate
  14. Nickel bisulphate 
Solution 15

 

Compounds

Acidic

radical

Basic

radical

Chemical formulae

Barium sulphate

SO42-

Ba2+

BaSO4

Bismuth nitrate

NO3-

Bi3+

Bi(NO3)3

Calcium bromide

Br-

Ca2+

CaBr2

Ferrous sulphide

S2-

Fe2+

FeS 

Chromium sulphate

SO42-

Cr3+

Cr2(SO4)3

Calcium silicate

SiO42-

Ca2+

Ca2SiO4

Potassium ferrocyanide

[Fe(CN)6]4-

K1+

K4[Fe(CN)6]

Stannic oxide

O2-

Sn2+

SnO2

Magnesium phosphate

(PO4)3-

Mg2+

Mg3(PO4)2

Sodium zincate

ZnO2-

Na1+

Na2ZnO2

 Stannic phosphate

(PO4)3-

Sn4+

Sn3(PO4)4

 Sodium thiosulphate

(S2O3)2-

Na1+

Na2S2O3

Potassium manganate

MnO42-

K1+

K2MnO4

Nickel bisulphate

HSO41-

Ni3+

Ni(HSO4)3

 

 

Question 16

Write the chemical names of the following compounds:

  1. Ca3(PO4)2 
  2. K2CO3
  3. K2MnO4 
  4. Mn3(BO3)2
  5. Mg(HCO3)2 
  6. Na4Fe(CN)6
  7. Ba(ClO3)2 
  8. Ag2SO3
  9. (CH3COO)2Pb  
  10. Na2SiO3 
Solution 16

Chemical names of compounds:

 

  1. Ca3(PO4)2 - Calcium phosphate 
  2. K2CO3 - Potassium carbonate
  3. K2MnO4 - Potassium manganate  
  4. Mn3(BO3)2 - Manganese (II) borate
  5. Mg(HCO3)2 - Magnesium hydrogen carbonate 
  6. Na4Fe(CN)6 - Sodium ferrocyanide
  7. Ba(ClO3)2 - Barium chlorate  
  8. Ag2SO3 - Silver sulphite
  9. (CH3COO)2Pb - Lead acetate 
  10. Na2SiO3 - Sodium silicate 

 

Question 17

Give the names of the following compounds.

  1. NaClO 
  2. NaClO2
  3. NaClO3
  4. NaClO4 
Solution 17
  1. NaClO - Sodium hypochlorite
  2. NaClO2 - Sodium chlorite
  3. NaClO3 - Sodium chlorate
  4. NaClO4 - Sodium perchlorate 
Question 18(a)

Complete the following statements by selecting the correct option :  

The formula of a compound represents

 i. an atom

 ii. a particle

 iii. a molecule

 iv. a combination 

Solution 18(a)

iii. The formula of a compound represents a molecule.

 

Question 18(b)

Complete the following statements by selecting the correct option :

The correct formula of aluminium oxide is

 i. AlO3

 ii. AlO2

 iii. Al2O3 

Solution 18(b)

iii. The correct formula of aluminium oxide is Al2O3.

Question 18(c)

Complete the following statements by selecting the correct option :

The valency of nitrogen in nitrogen dioxide (NO2) is

  1. one  
  2. two
  3. three
  4. four 
Solution 18(c)

iv. The valency of nitrogen in nitrogen dioxide (NO2) is four.

 

Question 19

Give the names of the elements and number of atoms of those elements present in the following compounds.

  1. Sodium sulphate
  2. Quick lime
  3. Baking soda (NaHCO3)
  4. Ammonia
  5. Ammonium dichromate
Solution 19
  1. Sodium sulphate - Na2SO4
    There are two sodium atoms, one sulphur atom and four oxygen atoms.
  1. Quick lime - CaO
    There is one calcium atom and one oxygen atom.
  1. Baking soda - NaHCO3
    There is one sodium, carbon and hydrogen atom and three oxygen atoms.
  1. Ammonia - NH3
    There is one nitrogen atom and three hydrogen atoms.
  1. Ammonium dichromate - (NH4)Cr2O7
    There two ammonium atoms, two chromium atoms and seven oxygen atoms.
Question 20

The formula of the sulphate of an element M is M2(SO4)3

Write the formula of its

  1. Chloride
  2. Oxide
  3. Phosphate
  4. Acetate
Solution 20

The valency of metal M is 3. So, the formulae are as follows:

  1. Chloride - MCl3
  2. Oxide - M2O3
  3. Phosphate - M(PO4)
  4. Acetate - M(CH3COO)3