Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers

Selina Publishers Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers

Rational Numbers Exercise 1A – Selina Concise Mathematics Class 8 ICSE Solutions

Question 1.
Add, each pair of rational numbers, given below, and show that their addition (sum) is also a rational number:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 1
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 2
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 3
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 4
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 5
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 6

Question 2.
Evaluate:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 7
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 8
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 9
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 10
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 11
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 12

Question 3.
Evaluate:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 13
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 14
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 15
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 16
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 17

Question 4.
For each pair of rational numbers, verify commutative property of addition of rational numbers:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 18
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 19
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 20
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 21
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 22
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 23
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 24
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 25

Question 5.
For each set of rational numbers, given below, verify the associative property of addition of rational numbers:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 26
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 27
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 28
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 29
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 30
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 31
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 32
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 33
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 34

Question 6.
Write the additive inverse (negative) of:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 35
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 36

Question 7.
Fill in the blanks:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 37
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 38

Question 8.
State, true or false:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 39
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1A 40

Rational Numbers Exercise 1B – Selina Concise Mathematics Class 8 ICSE Solutions

Question 1.
Evaluate:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 41
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 42
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 43
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 44
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 45

Question 2.
Subtract:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 46
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 47
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 48
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 49
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 50

Question 3.
The sum of two rational numbers is \(\frac { 9 }{ 20 }\). If one of them is \(\frac { 2 }{ 5 }\), find the other.
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 51

Question 4.
The sum of the two rational numbers is \(\frac { -2 }{ 3 }\). If one of them is \(\frac { -8 }{ 5 }\), find the other.
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 52

Question 5.
The sum of the two rational numbers is -6. If one of them is \(\frac { -8 }{ 5 }\), find the other.
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 53

Question 6.
Which rational number should be added to \(\frac { -7 }{ 8 }\) to get \(\frac { 5 }{ 9 }\) ?
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 54

Question 7.
Which rational number should be added to \(\frac { -5 }{ 9 }\) to get \(\frac { -2 }{ 3 }\) ?
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 55

Question 8.
Which rational number should be subtracted from \(\frac { -5 }{ 6 }\) to get \(\frac { 4 }{ 9 }\) ?
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 56

Question 9.
(i) What should be subtracted from -2 to get \(\frac { 3 }{ 8 }\)
(ii) What should be added to -2 to get \(\frac { 3 }{ 8 }\)
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 57
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 58

Question 10.
Evaluate:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 59
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 60
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 61
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1B 62

Rational Numbers Exercise 1C – Selina Concise Mathematics Class 8 ICSE Solutions

Question 1.
Evaluate:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 63
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 64
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 65

Question 2.
Multiply:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 66
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 67
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 68

Question 3.
Evaluate:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 69
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 70
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 71
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 72

Question 4.
Multiply each rational number, given below, by one (1):
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 73
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 74

Question 5.
For each pair of rational numbers, given below, verify that the multiplication is commutative:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 75
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 76
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 77

Question 6.
Write the reciprocal (multiplicative inverse) of each rational number, given below :
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 78
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 79

Question 7.
Find the reciprocal (multiplicative inverse) of:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 80
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 81

Question 8.
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 82
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 83
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 84

Question 9.
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 85
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 86
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 87

Question 10.
Name the multiplication property of rational numbers shown below :
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 88
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 89

Question 11.
Fill in the blanks:
(i) The product of two positive rational numbers is always ……………
(ii) The product of two negative rational numbers is always ……………
(iii) If two rational numbers have opposite signs then their product is always …………..
(iv) The reciprocal of a positive rational number is ………. and the reciprocal of a negative rational number is ……………
(v) Rational number 0 has ………….. reciprocal.
(vi) The product of a rational number and its reciprocal is ………..
(vii) The numbers ……….. and ……….. are their own reciprocals.
(viii) If m is reciprocal of n, then the reciprocal of n is ………….
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1C 90

Rational Numbers Exercise 1D – Selina Concise Mathematics Class 8 ICSE Solutions

Question 1.
Evaluate:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 91
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 92
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 93
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 94
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 95

Question 2.
Divide:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 96
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 97
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 98

Question 3.
The product of two rational numbers is -2. If one of them is \(\frac { 4 }{ 7 }\), find the other.
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 99

Question 4.
The product of two numbers is \(\frac { -4 }{ 9 }\). If one of them is \(\frac { -2 }{ 27 }\), find the other.
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 100

Question 5.
m and n are two rational numbers such that
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 101
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 102

Question 6.
By what number must \(\frac { -3 }{ 4 }\) be multiplied so that the product is \(\frac { -9 }{ 16 }\) ?
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 103

Question 7.
By what number should \(\frac { -8 }{ 13 }\) be multiplied to get 16?
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 104

Question 8.
If 3\(\frac { 1 }{ 2 }\) litres of milk costs ₹49, find the cost of one litre of milk?
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 105

Question 9.
Cost of 3\(\frac { 2 }{ 5 }\) metre of cloth is ₹88\(\frac { 1 }{ 2 }\). What is the cost of 1 metre of cloth?
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 106

Question 10.
Divide the sum of \(\frac { 3 }{ 7 }\) and \(\frac { -5 }{ 14 }\) by \(\frac { -1 }{ 2 }\).
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 107

Question 11.
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 108
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 109
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 110
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 111

Question 12.
The product of two rational numbers is -5. If one of these numbers is \(\frac { -7 }{ 15 }\), find the other.
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 112

Question 13.
Divide the sum of \(\frac{5}{8}\) and \(\frac{-11}{12}\) by the difference of \(\frac{3}{7}\) and \(\frac{5}{14}\)
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 113
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1D 114

Rational Numbers Exercise 1E – Selina Concise Mathematics Class 8 ICSE Solutions

Question 1.
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 115
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 116

Question 2.
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 117
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 118

Question 3.
Insert one rational number between (0 7 and 8 (ii) 3.5 and 5
(i) 2 and 3.2
(ii) 3.5 and 5
(iii) 2 and 3.2
(iv) 4.2 and 3.6
(v) \(\frac { 1 }{ 2 }\) and 2
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 119

Question 4.
Insert two rational numbers between
(i) 6 and 7
(ii) 4.8 and 6
(iii) 2.7 and 6.3
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 120
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 121

Question 5.
Insert three rational numbers between
(i) 3 and 4
(ii) 10 and 12
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 122

Question 6.
Insert five rational numbers between \(\frac { 3 }{ 5 }\) and \(\frac { 2 }{ 5 }\)
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 123

Question 7.
Insert six rational numbers between \(\frac { 5 }{ 6 }\) and \(\frac { 8 }{ 9 }\)
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 124
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 125

Question 8.
Insert seven rational numbers between 2 and 3.
Solution:
Selina Concise Mathematics Class 8 ICSE Solutions Chapter 1 Rational Numbers EX 1E 126

Selina Concise Mathematics Class 8 ICSE Solutions