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

Answer

Answer: (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

Answer

Answer: (c) 144
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.

Answer

Answer: (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.

Answer

Answer: (b) 2
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

Answer

Answer: (a) (ab)m
Hint:
Formula


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

Answer

Answer: (b) 1
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

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

Answer

Answer: (d) 25
Hint:
Formula


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

Answer

Answer: (b) 2
Hint:
Definition of exponent


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

Answer

Answer: (c) 10
Hint:
Definition of base


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

Answer

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

Answer

Answer: (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.

Answer

Answer: (c) 10-5
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.

Answer

Answer: (b) 2²
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.

Answer

Answer: (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

Answer

Answer: (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

Answer

Answer: (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.

Answer

Answer: (b) -2
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

Answer

Answer: (c) 3³
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

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

Answer

Answer: (b) 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.

Answer

Answer: (b) 1
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

Answer

Answer: (a) (5/6)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

Answer

Answer: (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

Answer

Answer: (c) 1
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.

Answer

Answer: (b) 1
Hint:
(-1) even natural number = 1


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

Answer

Answer: (a) -1
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.

Answer

Answer: (a) 1.496 × 1011
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

Answer

Answer: (a) 3 × 108
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

Answer

Answer: (a) 7 × 10-6
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

Answer

Answer: (a) 3.84467 × 108
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

Answer

Answer: (a) 1.275 × 10-5
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

Answer

Answer: (a) am+n
Hint:
Formula


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

Answer

Answer: (a) am-n
Hint:
Formula


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

Answer

Answer: (c) amn
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

Answer

Answer: (a) 1.6 × 10-3
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

Answer

Answer: (a) 3 × 10-6
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

Answer

Answer: (a) 8.848 × 103
Hint:
8848 = 8.848 × 10³


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

Answer

Answer: (a) 150000000000
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.

Answer

Answer: (a) 0.0000021
Hint:
2.1 × 10-6 = 0.0000021


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

Answer

Answer: (d) 25000
Hint:
2.5 × 104 = 25000


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

Answer

Answer: (a) 700000000
Hint:
0.07 × 1010 = 700,000,000.


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

Answer

Answer: (b) ¼
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

Answer

Answer: (a) 72
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

Answer

Answer: (c) 29
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

Answer

Answer: (a) 3-7
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

Answer

Answer: (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

Answer

Answer: (b) 312
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

Answer

Answer: (a) 6.95 × 105
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

Answer

Answer: (a) 5.036 × 105
Hint:
503600 = 5.036 × 105


Share:

0 comments:

Post a Comment

In Article

Definition List

Unordered List

Support