# CBSEtips.in

## Wednesday, 24 February 2021

### CBSE Class 8 Maths - MCQ and Online Tests - Unit 12 - Exponents and Powers

#### CBSE Class 8 Maths – MCQ and Online Tests –  Unit 12 – Exponents and Powers

Every year CBSE students attend Annual Assessment exams for 6,7,8,9,11th standards. These exams are very competitive to all the students. So our website provides online tests for all the 6,7,8,9,11th standards’ subjects. These tests are also very effective and useful for those who preparing for any competitive exams like Olympiad etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.

These online tests are based on latest CBSE syllabus. While attempting these, our students can identify their weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly

#### CBSE Class 8 Maths – MCQ and Online Tests – Unit 12 – Exponents and Powers

Question 1.
(2° + 4-1) × 2² is equal to
(a) 2
(b) 3
(c) 4
(d) 5

Hint:
(20 + 4-1) × 2² = (1 + $$\frac{1}{4}$$) × 4 = $$\frac{5}{4}$$ × 4 = 5

Question 2.
32 x 42 is equal to:
(a) 121
(b) 49
(c) 144
(d) 156

Hint:
By exponent law;
am x bm = (ab)m
32 x 42 = (3×4)2 = 122 = 144

Question 3.
(2-1 + 3-1 + 5-1)0 is equal to
(a) 2
(b) 3
(c) 5
(d) 1.

Hint:
(2-1 + 3-1 + 5-1)0 = 1 [? a0 = 1]

Question 4.
3m + 3-3 = 35 ? m is equal to
(a) 1
(b) 2
(c) 3
(d) 4.

Hint:
3m + 3-3= 35 ? 3m+3 = 35
? m + 3 = 5 ? m = 2

Question 5.
am × bm is equal to
(a) (ab)m
(b) (ab)-m
(c) am b
(d) abm

Hint:
Formula

Question 6.
a0 is equal to
(a) 0
(b) 1
(c) -1
(d) a.

Hint:
Formula

Question 7.
$$\frac{a^m}{b^m}$$ is equal to bm
(a) ($$\frac{a}{b}$$)m
(b) ($$\frac{b}{a}$$)m
(c) ($$\frac{a^m}{b}$$)m
(d) ($$\frac{a}{b^m}$$)m

Answer: (a) ($$\frac{a}{b}$$)m
Hint:
Formula

Question 8.
2 × 2 × 2 × 2 × 2 is equal to
(a) 24
(b) 2³
(c) 2²
(d) 25

Hint:
Formula

Question 9.
In 10², the exponent is
(a) 1
(b) 2
(c) 10
(d) 1.

Hint:
Definition of exponent

Question 10.
In 10² the base is
(a) 1
(b) 0
(c) 10
(d) 100.

Hint:
Definition of base

Question 11.
10-1 is equal to
(a) 10
(b) -1
(c) $$\frac{1}{10}$$
(d) –$$\frac{1}{10}$$

Answer: (c) $$\frac{1}{10}$$
Hint:
10-1 = $$\frac{1}{10^1}$$ = $$\frac{1}{10}$$

Question 12.
The multiplicative inverse of 2-3 is
(a) 2
(b) 3
(c) 3
(d) 23

Hint:
2-3. 2³ = 2-3+3 = 20 = 1

Question 13.
The multiplicative inverse of 105 is
(a) 5
(b) 10
(c) 10-5
(d) 105.

Hint:
105. 10-5 = 25-5 = 100 = 1

Question 14.
The multiplicative inverse of $$\frac{1}{2^2}$$ is 22
(a) 25
(b) 2²
(c) 2
(d) 1.

Hint:
$$\frac{1}{2^2}$$ = 2² = 1

Question 15.
The multiplicative inverse of 1010 is
(a) 10
(b) $$\frac{1}{10}$$
(c) 10-10
(d) 1010.

Hint:
10-10.1010 = 10-10+10 = 100 = 1

Question 16.
The multiplicative inverse of am is
(a) a
(b) m
(c) am
(d) a-m

Hint:
Definition of multiplicative inverse

Question 17.
5³ × 5-1 is equal to
(a) 5
(b) 5³
(c) 5-1
(d) 5²

Hint:
5³ × 5-1 = 53-1 = 5²

Question 18.
(- 2)-5 x (-2)6 is equal to
(a) 2
(b) -2
(c) -5
(d) 6.

Hint:
(-2)-5 × (-2)6 = (-2)-5+6 = (-2)1 = -2

Question 19.
3² × 3-4 × 35 is equal to
(a) 3
(b) 3²
(c) 3³
(d) 35

Hint:
3² × 3-4 × 35 = 32-4+5 = 3³

Question 20.
(-2)-2 is equal to
(a) $$\frac{1}{4}$$
(b) $$\frac{1}{2}$$
(c) –$$\frac{1}{2}$$
(d) –$$\frac{1}{4}$$

Answer: (a) $$\frac{1}{4}$$
Hint:
(-2)-2 = $$\frac{1}{(-2)^2}$$ = $$\frac{1}{4}$$

Question 21.
($$\frac{1}{2}$$)-4 is equal to
(a) 2
(b) 2-4
(c) 1
(d) 2-4

Hint:
($$\frac{1}{2}$$)-4 = $$\frac{(1)^{-4}}{(2)^{-4}}$$ = $$\frac{1}{(2)^{-4}}$$ = 24

Question 22.
(-2)m+1 × (-2)4 = (-2)6 ? m =
(a) 0
(b) 1
(c) -1
(d) none of these.

Hint:
(-2)m+1 × (-2)4 = (-2)6
? (-2)m+1+4 = (-2)6
? m + 5 = 6 ? m = 1

Question 23.
57/67 will give the value:
(a) (5/6)7
(b) (5/6)0
(c) (5/6)-7
(d) (6/5)-7

Hint:
By exponent law:
am/bm = (a/b)m
57/67 = (?)7

Question 24.
1000+200+50 is equal to
(a) 125
(b) 25
(c) 1/125
(d) 3

Hint:
By exponent law we know:
a0 = 1
1000 + 200 + 50 = 1 + 1 + 1 = 3

Question 25.
If (–3)m+1 × (-3)5 = (-3)7, then the value of m is:
(a) 5
(b) 7
(c) 1
(d) 3

Explanation: (-3)m+1 × (-3)5 = (-3)7
(-3)m+1+5 = (-3)7
(-3)m+6 = (-3)7
Since, base are equal on both the sides, hence if we compare the powers,
m + 6 = 7
m = 7 – 6 = 1

Question 26.
(-1)50 is equal to
(a) -1
(b) 1
(c) 50
(d) – 50.

Hint:
(-1) even natural number = 1

Question 27.
(-1)51 is equal to
(a) -1
(b) 1
(c) 51
(d) -51.

Hint:
(-1) odd natural number = -1

Question 28.
149600000000 is equal to
(a) 1.496 × 1011
(b) 1.496 × 1010
(c) 1.496 × 1012
(d) 1.496 × 108.

Hint:
149,600,000,000 = 1.496 × 1011

Question 29.
300000000 is equal to
(a) 3 × 108
(b) 3 × 107
(c) 3 × 106
(d) 3 × 109

Hint:
300,000,000 = 3 × 108

Question 30.
0.000007 is equal to
(a) 7 × 10-6
(b) 7 × 10-5
(c) 7 × 10-4
(d) 7 × 10-3

Hint:
0.000007 = 7 × 10-6

Question 31.
384467000 is equal to
(a) 3.84467 × 108
(b) 3.84467 × 103
(c) 3.84467 × 107
(d) 3.84467 × 106

Hint:
384467000 = 3.84467 × 108

Question 32.
0.00001275 is equal to
(a) 1.275 × 10-5
(b) 1.275 × 10-3
(c) 1.275 × 104
(d) 1.275 × 103

Hint:
0.00001275 = 1.275 × 10-5

Question 33.
am x am is equal to
(a) am+n
(b) am-n
(c) amn
(d) an-m

Hint:
Formula

Question 34.
am ÷ an is equal to
(a) am-n
(b) am+n
(c) amn
(d) an-m

Hint:
Formula

Question 35.
(am)n is equal to
(a) am+n
(b) am-n
(c) amn
(d) an-m

Hint:
Formula

Question 36.
0.0016 is equal to
(a) 1.6 × 10-3
(b) 1.6 × 10-2
(c) 1.6 × 10-4
(d) 1.6 × 10-5

Hint:
0.0016 = 1.6 × 10-3

Question 37.
0.000003 is equal to
(a) 3 × 10-6
(b) 3 × 106
(c) 3 × 105
(d) 3 × 10-5

Hint:
0.000003 = 3 × 10-6

Question 38.
8848 is equal to
(a) 8.848 × 103
(b) 8.848 × 10²
(c) 8.848 × 10
(d) 8.848 × 104

Hint:
8848 = 8.848 × 10³

Question 39.
1.5 × 1011 is equal to
(a) 150000000000
(b) 15000000000
(c) 1500000000
(d)1500000000000.

Hint:
1.5 × 1011 = 150,000,000,000

Question 40.
2.1 × 10-6 is equal to
(a) 0.0000021
(b) 0.000021
(c) 0.00021
(d) 0.0021.

Hint:
2.1 × 10-6 = 0.0000021

Question 41.
2.5 × 104 is equal to
(a) 25
(b) 250
(c) 2500
(d) 25000.

Hint:
2.5 × 104 = 25000

Question 42.
0.07 × 1010 is equal to
(a) 700000000
(b) 7000000
(c) 7000
(d) 7.

Hint:
0.07 × 1010 = 700,000,000.

Question 43.
The value of 2-2 is:
(a) 4
(b) ¼
(c) 2
(d) ½

Hint:
2-2 = 1/22 = ¼

Question 44.
The multiplicative inverse of 7-2 is:
(a) 72
(b) 7
(c) 1/72
(d) 1/7

Hint:
The multiplicative inverse of any value is the one which when multiplied by the original value gives a value equal to 1.
7-2 = 1/72
Hence, 72 x 1/72 = 1

Question 45.
22 x 23 x 24 is equal to:
(a) 224
(b) 2-5
(c) 29
(d) 2-9

Hint:
By laws of exponents:
am x an = am+n
22 x 23 x 24 = 22+3+4 = 29

Question 46.
3-2 x 3-5 is equal to:
(a) 3-7
(b) 3-3
(c) 3-10
(d) 37

Hint:
3-2 x 3-5 = (1/32) x (1/35)
= (1/32+5)
= (1/37)
= 3-7

Question 47.
54/52 is equal to:
(a) 56
(b) 5-6
(c) 5-2
(d) 52

Hint:
By exponent law:
am/an = am-n
54/52 = 54-2 = 52

Question 48.
The value of (34)3 is:
(a) 3
(b) 312
(c) 37
(d) None of the above

Hint:
By law of exponent:
(am)n = amn
(34)3 = 34×3 = 312

Question 49.
695000 is equal to
(a) 6.95 × 105
(b) 6.95 × 103
(c) 6.95 × 106
(d) 6.95 × 104

Hint:
695000 = 6.95 × 105

Question 50.
503600 is equal to
(a) 5.036 × 105
(b) 5.036 × 106
(c) 5.036 × 104
(d) 5.036 × 107