Solution for Class 9 Chemistry by TG57

Chapter1: The Language of Chemistry

Exercise :1 A 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 elemnt is taen and written in capitals(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 were 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 are very important in finding information about chemical compounds as it tell 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 SO4
- Mg+
b) (NH4)2SO4 SO4
- NH4
+
c) Al2(SO4)3 SO4
- Al
+3
d) ZnCO3 CO3
- Zn+2
e) Mg(OH)2 OH- Mg+2

12. Write the chemical formulae of sulphates of Aliminium, 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 whose valency is 3 and 3 is A2B3.

14. Match the following
Compound Formula
1.Boric acid ___ NaoH
2.Phosphoric acid ___SiO2
3.Nitrous acid ___Na2CO3
4.Nitric acid __KOH
5.Sulphorous acid ___CaCO3
6.Sulphuric acid __NaHCO3
7.Hydrochloric acid __H2S
8.Silica (Sand) ___H2O
9.Caustic soda ( Sodium Hydroxide)__ PH3
10.Caustic potash( potassium hydroxide) __CH4
11.Washing soda( Sodium carbonate) __NH3
12.Baking Soda ( Sodium bi carbonate) __HCl
13.Lime stone ( calcium carbonate)__ H2SO3
14.Water __HNO3
15.Hydrogen Sulphide __HNO2
16.Ammonia ___H3BO3
17.Phosphine ___H3PO4
18.Methane ___H2SO4
Solution:
1.Compound Formula
2.Boric acid --H3BO3
3.Phosphoric acid --H3PO4
4.Nitrous acid --HNO2
5.Nitric acid --HNO3
6.Sulphorous acid --H2SO3
7.Sulphuric acid --H2SO4
8.Hydrochloric acid --HCl
9.Silica (Sand) --SiO2
10.Caustic soda ( Sodium Hydroxide) --NaOH
11.Caustic potash( potassium hydroxide) --KOH
12.Washing soda( Sodium carbonate) --Na2CO3
13.Baking Soda ( Sodium bi carbonate) --NaHCO3
14.Lime stone ( calcium carbonate) --CaCO3
15.Water --H2O
16.Hydrogen Sulphide --H2S
17.Ammonia --NH3
18.Phosphine --PH3
19.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:



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(Cl)3)2
h) Ag2SO3
i) (CH3COO)2Pb
j) Na2SiO3

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.

Solution:
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 :1 B 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 Magnessium 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 + O2
h) S + H2SO4 SO2+ H2O
i) S + HNO3 H2SO4 + NO2 + H2O
j) MnO2 + HCl MnCl2 + H2O + SO2
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(NO)3+ H2O + NO2