ICSE Selina Solution for Class 9 Chemistry Chapter 1 : The Language Of Chemistry

ICSE Selina Concise Solution for Class 9 Chemistry Chapter 1- Free PDF Download

ICSE Selina Solution for Class 9 Chemistry Chapter 1 – The Language Of Chemistry provides you with detailed answers to all the exercise questions provided in Selina publication ICSE class 9 Chemistry textbook. This solution helps you to attain perfection in the topics involved in the chapter The Language Of Chemistry. To score good marks in Chemistry examination, students need to focus on this study material thoroughly.

This Class 9 Selina Solutions helps you to attain a basic knowledge of Chemistry such as symbols, valency, radicals, compounds, chemical equations, atomic weights, molecular weight and calculation of relative molecular mass and percentage composition of a compound.

ICSE Selina solutions act as a perfect study material that is required for your ICSE examination. Studying this ICSE Selina Solution for Class 9 Chemistry will also help you to get a basic knowledge of introduction to Chemistry.

Important topics covered in ICSE Selina Solution for Class 9 Chemistry Chapter 1 The Language Of Chemistry

  • Introduction
  • Symbols
  • Valency
  • Formula
  • Radicals
  • Writing chemical formulae
  • Naming certain compounds
  • Calculating the valency from the formula
  • Chemical equation
  • Relative atomic mass (Atomic weight)
  • Relative molecular mass (Molecular weight)
  • Percentage composition
  • Empirical formula of a compound

Download PDF of ICSE Selina Solution for Class 9 Chemistry Chapter 1 The Language Of Chemistry

icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 01
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 02
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 03
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 04
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 05
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 06
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 07
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 08
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 09
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 10
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 11
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 12
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 13
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 14
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 15
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 16
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 17
icse class 9 chemistry jul22 selina solutions chapter 1 the language of chemistry 18

Access Answers of Selina publication ICSE Class 9 Chemistry Chapter 1 The Language Of Chemistry

Exercise 1A Page No: 9-10

1. What is a symbol? What information does it convey?

Solution:

Short form of atom of specific element or the abbreviations used to refer names of the element is known as symbol.

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.

2. Why is the symbol S for Sulphur, but Na for Sodium and Si for Silicon.

Solution:

While naming an element first letter of the element is taken and written in capital (e.g. for sulphur, we use the symbol S). In case if the letter is already adopted. We use a symbol derived from Latin word of the element 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).

3. Write the full form of IUPAC. Name the elements represented by the following Symbols: Au, Pb, Sn, Hg

Solution:

IUPAC stands for The International Union of Pure and Applied Chemistry (IUPAC)

Au – Gold

Pb – Lead

Sn – Tin

Hg – Mercury

4. If the symbol for cobalt, Co was written as CO. What would be wrong with it?

Solution:

If we write CO it means it consist of two non-metals namely Carbon and Oxygen and it would represent Carbon- monoxide but not Cobalt.

5. What do the following symbols stand for?

a) H b) H2 c) 2H d) 2H2

Solution:

a) H stands for one atom of Hydrogen

b) H2 stands for one molecule of Hydrogen

c) 2H stands for 2 atoms of Hydrogen

d) 2H2 stands for 2 molecules of Hydrogen.

6. What is meant by atomicity? Name a diatomic element.

Solution:

A set of atoms of the same type together forms a molecule of the element. The number of atoms in a molecule of an element is called its atomicity.

Examples of diatomic elements are H2 – Hydrogen, O2 – Oxygen, N2 – Nitrogen

7. a) Explain the terms valency and variable valency

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

Solution:

a) Valency is the capacity of an atom to lose, gain or share atoms during a chemical reaction is called its valency. Sometimes atom of an element can lose more electron than they are present which means they lose electron from its penultimate shell. Such an element is said to exhibit variable valency.

b) If an element exhibits two different positive valencies, then

1. For the lower valency, use the suffix -OUS at the end of the name of the metal

2. For the higher valency, use the suffix -IC at the end of the name of the metal.

8. Give the formula and valency of

a) aluminate

b) chromate

c) aluminium

d) cupric

Solution:

Name

Formula

Valency

Aluminate

AlO2

-2

Chromate

CrO4

-2

Aluminium

Al

+3

Cupric

Cu

+2

9. a) What is a chemical formula?

b) What is the significance of a formula? Give an illustrate.

Solution:

a) Chemical formula is a symbolic representation of the number of atoms present in a molecule of that substance.

b) Significance of Chemical Formula

Chemical formula is very important in finding information about chemical compounds as it tells us about the elements and the number of atoms in a substance

Example – Salt – NaCl, ethanol C2H6O because the molecule of ethanol contains two Carbon, 6 Hydrogen and 1 Oxygen atom.

10. What do you understand by following terms?

a) Acid radical b) Basic radical

Solution:

a) Negatively charged radical is called as acidic radical.

b) Positively charged radical is called as basic radical.

11. Select the basic radical in the following compounds

a) MgSO4

b) (NH4)2

c) Al2(SO4)3

d) ZnCO3

e) Mg(OH)2

Solution:

Acid Radical

Basic radical

a) MgSO4

SO42-

Mg2+

b) (NH4)2SO4

SO42-

NH4+

c) Al2(SO4)3

SO42-

Al3+

d) ZnCO3

CO32-

Zn2+

e) Mg(OH)2

OH

Mg2+

12. Write the chemical formulae of sulphates of Aluminium, Ammonium and Zinc.

Solution:

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, ZnSO4

13. The valency of 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:

Formula of compound having valency of elements are 3 and 2 is A2B3.

14. Match the following

Compound

Formula

Boric acid

NaoH

Phosphoric acid

SiO2

Nitrous acid

Na2CO3

Nitric acid

KOH

Sulphorous acid

CaCO3

Sulphuric acid

NaHCO3

Hydrochloric acid

H2S

Silica (Sand)

H2O

Caustic soda (Sodium Hydroxide)

PH3

Caustic potash (Potassium hydroxide)

CH4

Washing soda (Sodium carbonate)

NH3

Baking Soda (Sodium bi carbonate)

HCl

Lime stone (Calcium carbonate)

H2SO3

Water

HNO3

Hydrogen Sulphide

HNO2

Ammonia

H3BO3

Phosphine

H3PO4

Methane

H2SO4

Solution:

Compound

Formula

Boric acid

H3BO3

Phosphoric acid

H3PO4

Nitrous acid

HNO2

Nitric acid

HNO3

Sulphorous acid

H2SO3

Sulphuric acid

H2SO4

Hydrochloric acid

HCl

Silica (Sand)

SiO2

Caustic soda (Sodium Hydroxide)

NaOH

Caustic potash (Potassium hydroxide)

KOH

Washing soda (Sodium carbonate)

Na2CO3

Baking Soda (Sodium bi carbonate)

NaHCO3

Lime stone (Calcium carbonate)

CaCO3

Water

H2O

Hydrogen Sulphide

H2S

Ammonia

NH3

Phosphine

PH3

Methane

CH4

15. Write the basic and acidic radicals of the following and then write the chemical formulae of these compounds.

a) Barium sulphate

b) Bismuth nitrate

c) calcium bromide

d) Ferrous sulphide

e) Chromium sulphate

f) Calcium silicate

g) Stannic oxide

h) Sodium Zincate

i) Magnesium phosphate

j) Sodium thiosulphate

k) Stannic phosphate

l) Nickel-bi-silphate

m) Potassium mangnate

n) Potassium ferrocynide

Solution:

Compounds

Acidic radical

Basic radical

Chemical formulae

a) Barium sulphate

SO4-2

Ba+2

BaSO4

b) Bismuth nitrate

NO3

Bi+3

Bi(NO3)3

c) calcium bromide

Br

Ca+2

CaBr2

d) Ferrous sulphide

S2-

Fe+2

FeS

e) Chromium sulphate

SO42-

Cr+3

Cr2(SO4)3

f) Calcium silicate

SiO42-

Cr+3

Cr2(SO4)3

g) Stannic oxide

O2-

Sn+2

SnO2

h) Sodium Zincate

ZnO2-

Na+1

Na2ZnO2

i) Magnesium phosphate

PO43-

Mg+2

Mg3(PO4)2

j) Sodium thiosulphate

(S2O3)2-

Na+1

Na2S2O3

k) Stannic phosphate

(PO4)3-

Sn+4

Sn3(PO4)4

l) Nickel-bi-silphate

H2SO4-

Ni+3

NiH(SO4)3

m) Potassium mangnate

MnO42-

K+1

K2MnO4

n) Potassium ferrocynide

[Fe(CN)6]4-

K+1

K4[Fe(CN)6]

16. Write chemical names of the following compounds:

a) Ca3(PO4)2

b) K2CO3

c) K2MnO4

d) Mn3(BO3)2

e) Mg(HCO3)2

f) Na4Fe(CN)6

g) Ba(Cl3)2

h) Ag2SO3

i) (CH3COO)2Pb

j) Na2SiO3

Solution:

a) Calcium phosphate

b) Potassium carbonate

c) Potassium manganate

d) Manganese(II) Borate

e) Magnesium bicarbonate.

f) Sodium ferrocyanide

g) Barium Chlorate

h) Silver sulfite

i) Lead(II) acetate

j) Sodium silicate

17. Give the names of the following compounds

a) KClO

b) KClO2

c) KClO3

d) KClO4

Solution:

a) Potassium hypochlorite

b) Potassium chlorite

c) Potassium chlorate

d) Potassium per chlorate

18. Complete the following statements by selecting the correct option.

a) The formula of a compound represents

i) an atom

ii) a particle

iii) a molecule

iv) a combination

b) The correct formula of aluminium oxide is

i) AlO3

ii) AlO2

iii) Al2O3

iv) Al3O2

c) The valency of Nitrogen in Nitrogen di oxide (NO2) is

i) One

ii) Two

iii) Three

iv) Four

Solution:

a) The formula of a compound represents a molecule

b) The correct formula of aluminium oxide is Al2O3

c) The valency of Nitrogen in Nitrogen di oxide (NO2) is four

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

a) Sodium sulphate

b) Quick lime

c) Baking soda (NaHCO3)

d) Ammonia

e) Ammonium dichromate

Solution:

a) Sodium sulphate

Chemical formula is Na2SO4

Atoms – 2 sodium, one Sulphur and 4 oxygen atoms.

b) Quick lime

Chemical formula is CaO

Atoms – one Calcium atom and 1 oxygen atom

c) Baking soda (NaHCO3)

Chemical formula of is NaHCO3

Atoms – 1 Sodium, 1 hydrogen, 1 carbon and 3 oxygen atoms.

d) Ammonia

Chemical formula is NH3

Atoms – 3 hydrogen and 1 nitrogen atom.

e) Ammonium dichromate

Chemical formula is (NH4)2Cr2O7.

Atoms – 2 ammonium, 2 chromium and 7 oxygen atoms.

20. The formula of the sulphate of an element M is M2(SO4)3. Write the formula of it.

a) Chloride

b) Oxide

c) Phosphate

d) Acetate

Solution:

Answer is a) Chloride

Exercise 1B Page No: 15

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

Solution:

A chemical equation is a symbolic representation of a chemical reaction. Here we use symbols and formulas of the substance involved in the reaction.

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

2. State the information conveyed by the following equation.

Zn(s) + 2HCl(aq) ZnCl2(aq) + H2

Solution:

This chemical equation shows ‘single displacement reaction’, in which a non-metal is displaced by a metal. Here, non-metal is hydrogen which is evolved as gas. It is displaced by the metal zinc. In the given equation – Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g), Zinc (Zn) is a reductant metal that displaces hydrogen (H2) from aqueous solution of Hydrochloric acid (HCl).

3. Write the limitation of reaction given in question 2.

Solution:

HCl will be the limiting reagent in the reaction and Zn will be excess reagent.

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

a) Carbon + Oxygen → Carbon-di-oxide

b) Nitrogen + Oxygen → Nitrogen monoxide

c) Calcium + Nitrogen → Calcium nitride

d) Calcium oxide + carbon dioxide → Calcium carbonate

e) Magnesium + Sulphuric acid → Magnesium sulphate + Hydrogen

Solution:

a) 2C + O2 → CO2

b) N2 + O2 → 2NO

c) 3Ca(s) + N2(g) → Ca3N2

d) CaO + CO2 → CaCO3

e) Mg(s) + H2SO4(aq) → MgSO4(aq) + H2(g)

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 + NH3 → Pb + H2O + N2

f) Pb3O4 → PbO + O2

g) PbS + O2 → PbO + 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 + Cl2 → KCl + KClO + H2O

m) NO2 + H2O → HNO2 + HNO3

n) Pb3O4 + HCl → PbCl2 + H2O + Cl2

o) H2O + Cl2 → HCl + 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:

a) 3Fe + 4H2O → Fe3O4 + 4H2

b) 3Ca + N2 → Ca3N2

c) Zn + 2KOH → K2ZnO2 + H2

d) Fe2O3 + 3CO → 2Fe + 3CO2

e) 3PbO + 2NH3 → 3Pb + 3H2O + N2

f) 2Pb3O4 → 6PbO + O2

g) 2PbS + 3O2 → 2PbO + 2SO2

h) S + 2H2SO4 → 3SO2 + 2H2O

i) S + 6HNO3 → H2SO4 + 6NO2 + 2H2O

j) MnO2 + 4HCl → MnCl2 + 2H2O + Cl2

k) C + 2H2SO4 → CO2 + H2O + SO2

l) 2KOH + Cl2 → KCl + KClO + H2O

m) 2NO2 + H2O → HNO2 + HNO3

n) Pb3O4 + 8HCl → 3PbCl2 + 4H2O + Cl2

o) 2H2O + 2Cl2 → 4HCl + O2

p) 2NaHCO3 → Na2CO3 + H2O + CO2

q) 2HNO3 + H2S → 2NO2 + 2H2O + S

r) P + 5HNO3 → 5NO2 + H2O + H3PO4

s) Zn + 4HNO3 → Zn(NO3)2 + 2H2O + 2NO2

Exercise 1C Page No: 18-20

1. Fill in the blanks

a) Dalton used symbol _____ for oxygen _______ for hydrogen.

b) Symbol represents _______ atom(s) of an element.

c) Symbolic expression for a molecule is called ________.

d) Sodium chloride has two radicals. Sodium is a ________ radical, while chloride is a ___ radical.

e) Valency of Phosphorous in PCl3 is _____, in PCl5 is _____.

f) Valency of iron in FeCl2 is ____ and in FeCl3 it is _____.

g) Formula of iron (III) carbonate is ______.

Solution:

a) Dalton used symbol [O] for oxygen, [H] for hydrogen.

b) Symbol represents gram atom(s) of an element.

c) Symbolic expression for a molecule is called molecular formula.

d) Sodium chloride has two radicals. Sodium is a basic radical, while chloride is an acid radical.

e) Valency of Phosphorous in PCl3 is 3, in PCl5 is 5,

f) Valency of iron in FeCl2 is 2 and in FeCl3 it is 3.

g) Formula of iron (III) carbonate is Fe2[CO3]3.

2. Complete the following table

Acid Radical →

Basic radical

Chloride

Nitrate

Sulphate

Carbonate

Hydroxide

Phosphate

Magnesium

MgCl2

Mg(NO)2

MgSO4

MgCO3

Mg(OH)2

Mg3(PO4)2

Sodium

Zinc

Silver

Ammonium

Calcium

Iron (II)

Potassium

Solution:

Acid Radical →

Basic radical

Chloride

Nitrate

Sulphate

Carbonate

Hydroxide

Phosphate

Magnesium

MgCl2

Mg(NO)2

MgSO4

MgCO3

Mg(OH)2

Mg3(PO4)2

Sodium

NaCl

NaNO3

Na2SO4

Na2CO3

NaOH

Na3PO4

Zinc

ZnCl2

ZnNO3

ZnSO4

ZnCO3

Zn(OH)2

Zn3(PO4)2

Silver

AgCl

AgNO3

Ag2SO4

AgCO3

AgOH

Ag3PO4

Ammonium

NH4Cl

NH4NO3

(NH4)2SO4

(NH4)2CO3

NH4OH

(NH4)3(PO4)2

Calcium

CaCl2

CaNO3

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

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

a) Write the equation

b) Check whether it is balanced, if not balance it.

c) Find the weights of reactants and products.

d) State the law that this equation satisfies?

Solution:

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

Thus, 228.5 g of reactants → 228.5 g of products

d) This equation states law of conservation of mass where mass is neither created nor destroyed.

4. What information does the following chemical equations convey?

a) Zn + H2SO4 → ZnSO4 + H2

b) Mg + 2HCl → MgCl2 + H2

Solution:

a) This equation shows the result of a chemical change. When one molecule of zinc and one molecule of sulphuric acid reacts, it results in the production of one molecule of zinc sulphate and one molecule of hydrogen.

b) This equation shows reaction of Magnesium with HCl which gives magnesium chloride and liberated Hydrogen gas.

5. a) What are poly-atomic ions? Give two examples

b) Name the fundamental law involved in every equation

Solution:

a) A charged ion that consists of two or more covalently bounded atoms are called as polyatomic ions. Eg: CaCO3, MgSO4

b) Fundamental law involved in every equation is “the law of conservation of mass”.

6. What is the valency of?

a) Fluorine in CaF2

b) Sulphur in SF6

c) Phosphorous in PH3

d) Carbon in CH4

e) Nitrogen in the following compound

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

f) Manganese in MnO2

g) Copper in Cu2O

h) Magnesium in Mg3N2

Solution:

a) Valency of fluorine in CaF2 is -1

b) Valency of sulphur in SF6 is -6

c) Valency of phosphorus in PH3 is +3

d) Valency of carbon in CH4 is +4

e) Valency of nitrogen in the given compounds:

i) N2O3 = +3

ii) N2O5 = +5

iii) NO2 = +4

iv) NO = +2

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

Solution:

An equation should n be balanced to make it comply with the law of conservation of matter which states that matter is neither created nor destroyed in the course if a chemical reaction. An unbalanced equation either deletes or adds extra atoms in the equation.

e.g. KNO3 → KNO2 + O2

In this equation number of atoms in left and right side are not equal hence the balanced equation will be written as.

2KNO3 → 2KNO2 + O2

8. Write the balanced chemical equations of the following word equations

a) Sodium hydroxide + Sulphuric acid → Sodium Sulphate + Water

b) Potassium bicarbonate + Sulphuric acid → Potassium Sulphate + Carbon di oxide + Water

c) Iron + Sulphuric acid → Ferrous sulphate + Hydrogen

d) Chlorine + Sulphur di oxide + Water → Sulphuric acid + Hydrogen Chloride

e) Silver Nitrate → Silver + Nitrogen di oxide + Oxygen

f) Copper + Nitric acid → Copper nitrate + Nitric oxide + water

g) Ammonia + Oxygen → Nitric oxide + Water

h) Barium chloride + Sulphuric acid → Barium Sulphate + Hydrochloric acid

i) Zinc sulphide + Oxygen → Zinc oxide + Sulphur dioxide

j) Aluminium carbide + Water → Aluminium hydroxide + methane

k) Iron Pyrites + Oxygen → Ferric oxide + Sulphur di oxide

l) Potassium permanganate + Hydrochloric acid → Potassium chloride + Manganese chloride + chlorine + Water

m) Aluminium sulphate + Sodium hydroxide → Sodium sulphate + Sodium meta aluminate + Water

n) Aluminium + Sodium hydroxide + Water → Sodium meta aluminate + Hydrogen

o) Potassium dichromate + Sulphuric acid → Potassium sulphate + Chromium sulphate + Water + Oxygen

p) Potassium dichromate + Hydrochloric acid → Potassium chloride + Chromium chloride+ Water + Chlorine

q) Sulphur + Nitric acid → Sulphuric acid + Nitrogen dioxide + Water

r) Sodium chloride + Manganese dioxide + Sulphuric acid → Sodium hydrogen sulphate + Manganese sulphate + Water+ Chlorine

Solution:

a) 2NaOH + H2SO4 → Na2SO4 + 2H2O

b) 2KHCO3 + H2SO4 → K2SO4 + 2CO2 + 2H2O

c) Fe + H2SO4 → FeSO4 + H2

d) Cl2 + SO2 + 2H2O → H2SO4 + 2HCl

e) 2AgNO3 → 2Ag + 2NO2 + O2

f) 3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O

g) 4NH3 + 5O2 → 6H2O + 4NO

h) BaCl2 + H2SO4 → BaSO4 + 2HCl

i) 2ZnS + 3O2 → 2ZnO + 2SO2

j) Al4C3 + 12H2O → 4Al(OH)3 + 3CH4

k) 4FeS2 + 11O2 → 2Fe2O3 + 8SO2

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

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

n) 2Al + 2NaOH + 2H2O → 2NaAlO2 + 3H2

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

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

q) S + 6HNO3 → H2SO4 + 6NO2 + 2H2O

r) 2KI + 2MnO2 + 4H2SO4 → I2 + 2KHSO4 + 2MnSO4 + 4H2O

9. a) Define atomic mass unit

b) Calculate the molecular mass of the following

i) Na2SO4.10H2O ii) (NH4)2CO3 iii) (NH2)2CO iv) Mg3N2

Give atomic mass of Na = 23, H = 1, O = 16, C = 12, N = 14, Mg = 24, S = 32

Solution:

a) The atomic mass unit (amu) is defined as 1/12th of the mass of an atom of carbon

1 a.m.u. = 1.67 x 10-24m =1.67 x 1027 kg

1 gm mass = 6.02 x 1023 a.m.u. and 1 kg mass = 6.02 x 1026 a.m.u.

b) i) The relative molecular mass of CuSO4.5H2O

= 63.5 + 32 + (16 x 4) + 5 (2 + 16)

= 159.5 + 90

= 249.5 2

ii) The relative molecular mass of (NH4)2CO3 = N2H8CO3

= 14 x 2 + 1 x 8 + 12 + 3 x 16

= 28 + 8 + 12 + 48

= 96

iii) The relative molecular mass of (NH2)2CO = N2H4CO

= 2 x 14 + 1 x 4 +12 + 16

= 28 + 4 + 12 + 16

= 60

iv) The relative molecular mass of Mg3N2

= 3 x 24 + 2 x 14

= 72 + 28

= 100

10. Choose the correct answer from the options given below

a) Modern atomic symbols are based on the methods proposed by

(i) Bohr (ii) Dalton (iii) Berzelius (iv) Alchemist

b) The number of carbon atoms in a hydrogen carbonate radical is

(i) one (ii) two (ii) three (iv) four

c) The formula of Iron(III) Sulphate is

(i)Fe3SO4 (ii) Fe(SO)3 (iii) Fe(SO4)3 (iv)FeSO4

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

(i)1:8 (ii) 1:16 (iii) 1:32 (iv) 1:64

(e) The formula of sodium carbonate is Na, CO, and that of calcium hydrogen carbonate is (i)CaHCO3 (ii) Ca(HCO3)2 (iii) CaHCO3 (iv) Ca(HCO)3

Solution:

a) Answer is (iii) Berzelius

b) Answer is (i) One

c) Answer is (iii) Fe2(SO4)3

d) Answer is (i) 1: 8

e) Answer is (ii) Ca(HCO3)2

11. Correct the following statements

(a) A molecular formula represents an element

(b) Molecular formula of water is H2O2

(c) A molecule of Sulphur is monoatomic

(d) CO and Co both represent cobalt

(e) Formula of Iron(III) oxide is FeO

Solution:

a) Molecular formula represents molecule of an element or a compound.

b) Molecular formula of water is H2O

c) A molecule of Sulphur is diatomic

d) CO represents carbon monoxide and Co represent cobalt

e) Formula of Iron(III) oxide is Fe2O3

12. Calculate the relative molecular masses of:

(a) CHCI3

(b) (NH4)2Cr2O7

(c) CuSO4.5H2O

(d) (NH4)2SO4

(e) CH3COONa

(f) Potassium chlorate

(g) Ammonium chloroplatinate (NH4)2PtCl6

[At. mass: C = 12,H = 1, O = 16, Cl = 35.5, N = 14, Cu = 63.5, S = 32, Na = 23, K = 39, Pt = 195, Ca = 40, P = 31, Mg = 24]

Solution:

(a) Relative molecular mass of CHCI3

= 12 + 1 + (3 x 35.5)

= 12 + 1 + 106.5

= 119.5 2

(b) Relative molecular mass of (NH4)2Cr2O7

= (14 x 2) + (1 x 8) + (52 x 2) + (16 x 7)

= 28 + 8 + 104 + 112

= 252

(c) Relative molecular mass of CuSO4.5H20

= 63.5 + 32 + (16 x 4) + 5(2 + 16)

= 159.5 + 90

= 249.5

(d) Relative molecular mass of (NH4)2SO4

= (2 x 14) + (8 x 1) + 32 + (4 x 16)

= 28 + 8 + 32 + 64

= 132

(e) Relative molecular mass of CH3COONa

= (12 x 2) + (1 x 3) + (16 x 2) + 23

= 24 + 3 + 32 + 23

= 82

(f) Potassium chlorate (KClO3)

= 39.1 + 35.5 + 16 x 3

= 39.1 + 35.5 + 48

= 122.6

(g) Ammonium chloroplatinate (NH4)2PtCl6

= (14 x 2) + (1 x 8) + 195.08 + (35.5 x 6)

= 28 + 8 + 195.08 + 213

= 444.08

13. Give the empirical formula of:

(a) Benzene (C6H6) (b) Glucose (C6H12O6) (c) Acetylene (C2H2) (d) Acetic acid (CH3COOH)

Solution:

(a) Benzene – CH

(b) Glucose – CH2O

(c) Acetylene – CH

(d) Acetic acid – CH2O

14. Find the percentage mass of water in Epsom salt MgSO4.7H2O.

Solution:

Relative molecular mass of MgSO4.7H2O

= 24 + 32 + (16 x 4) + 7(2 + 16)

= 24 + 32 + 64 + 126

= 246

26 g of Epsom salt contains 126 g of water of crystallisation.

So, 100 g of Epsom salt contains (100 x 126/246) g of water

Thus, percentage mass of H2O in MgSO4.7H2O = 51.2

15. Calculate the percentage of phosphorus in:

(a) Calcium hydrogen phosphate Ca(H2PO4)2

(b) Calcium phosphate Ca3(PO4)2

Solution:

(a) Relative molecular mass of Ca(H2PO4)

= 40.07 + (1 x 4) + (30.9 x 2) + (16 x 8)

= 40.07 + 4 + 61.8 + 128

= 233.87

Now, 233.87 g of Ca(H2PO4) contains 61.8 g of P

So, 100 g Ca(H2PO4) contains

(100 x 61.8)/233.87 = 26.42 g

Thus, the percentage of phosphorous in Ca(H2PO4) is 26.42%

(b) Relative molecular mass of Ca3(PO4)2

= (40.07 x 3) + (30.9 x 2) + (16 x 8)

= 120.21 + 61.8 + 128

= 310.01

Now, 310.01 g of Ca3(PO4)2 contains 61.8 g of P

So, 100 g Ca3(PO4)2 contains

(100 x 61.8)/310.01 = 19.93 g

Thus, the percentage of phosphorous in Ca3(PO4)2 is 19.93%

16. Calculate the percentage composition of each element in Potassium chlorate, KClO3.

Solution:

Relative molecular mass of KClO3

= 39.09 + 35.5 + (3 x 16)

= 122.59 g

So, 122.59 g of KClO3 contains 39.09 g of K

Hence, 100 g of KClO3 contains

= (100 x 39.09)/122.59

= 31.9 g

Also, 122.59 g of KClO3 contains 35.5 g of Cl

Hence, 100 g of KClO3 contains

= (100 x 35.5)/122.59

= 28.9 g

And, 122.59 g of KClO3 contains 48 g of O

Hence, 100 g of KClO3 contains

= (100 x 48)/122.59

= 39.1 g

Therefore, the percentage composition of K, Cl and O in KClO3 are 31.9%, 28.9% and 39.1% respectively.

17. Urea is a very important nitrogenous fertilizer. Its formula is CH4N2O. Calculate the percentage of carbon in urea. (C = 12, O = 16, N = 14 and H = 1)

Solution:

Element

No of atoms

Atomic mass

Total

N

2

14

28

C

1

12

12

H

4

1

4

O

1

16

16

⇒ 12 + 16 + 28 + 4 = 60

Hence, relative molecular mass of urea = 60

Thus,

Percentage of carbon = Weight of carbon/Total weight of urea x 100

= 12/60 x 100

= 20%

To Study more solutions Click here

BYJU’S provides Selina Solutions for your reference. You can access these solutions and download for free for your reference. For ICSE Sample papers, Previous year question papers, Important question for all the classes and subjects visit BYJU’S website or download BYJU’S Learning App.

Frequently Asked Questions on The Language of Chemistry

What is a symbol?

Short form of an atom of a specific element or the abbreviations used to refer names of the element is known as symbol.

Full form of IUPAC?

IUPAC stands for The International Union of Pure and Applied Chemistry (IUPAC)

Hydrogen Symbol?

H stands for one atom of Hydrogen

H2 stands for one molecule of Hydrogen

2H stands for 2 atoms of Hydrogen

2H2 stands for 2 molecules of Hydrogen

What is meant by atomicity?

A set of atoms of the same type together forms a molecule of the element. The number of atoms in a molecule of an element is called its atomicity.

Define the term valency?

Valency is the capacity of an atom to lose, gain or share atoms during a chemical reaction is called its valency.

What is a chemical formula?

A chemical formula is a symbolic representation of the number of atoms present in a molecule of that substance.

What is Acid radical?

Negatively charged radical is called as acidic radical.

What is Basic radical?

Positively charged radical is called a basic radical.

What are polyatomic ions?

A charged ion that consists of two or more covalently bonded atoms are called polyatomic ions

BOOK

Free Class