Important Questions Class 8 Maths Chapter 12 Exponents And Powers

Important questions for class 8 maths chapter 12 – exponents and powers, with solutions are provided here by our subject experts. Practice these questions to score better marks in the exam as it covers the latest CBSE syllabus (2019-2020) and is as per NCERT book/curriculum.

The chapter exponents and powers will explain to represent very large numbers or very small numbers in a standard form. Students can reach us at Important Questions Class 8 Math to get important questions and solutions for all the chapters of Maths 8th Class.

Also Check:

Exponents And Powers Important Questions For Class 8 (Chapter 12)

Some of the important short answer type questions and long answer type questions from exponents and powers are given below.

Short Answer Type Questions

1. Find the value of (40 + 4-1) × 22

Solution:

(40 + 4 -1) × 22 = (1 + ¼) × 4

= 4+1=5

2. Solve 3-4 and (½)-2

Solution:

We know, b-n = 1/bn

So, 3-4 = 1/34 = 1/81

And, (½)-2 = 1-2/2-2 = 22/12 = 4

3. Simplify the following expression and express the result in positive power notation:

(−4)5 ÷ (−4)8

Solution:

Using am ÷ an = am-n

(−4)5 ÷ (−4)8 = (-4)5/(-4)8

⇒ (-4)5-8 = 1/ (-4)3

4. Evaluate a2 × a3 × a-5

Solution:

a2 × a3 × a-5 = a2+3-5

= a5-5

= a0 = 1

5. Express 4-3 as a power with base 2.

Solution:

4-3 can be written as:

4-3 = (22)-3

Now, by using exponential law i.e. (am)n = amn

4-3 = 2-6 (which is in base 2 form).

Long Answer Type Questions

6. Evaluate (√4)-3

Solution:

(√4)-3 = (4½)-3

= 4-3/2 = 1/ 43/2

= 1/(43)½ = 1/(64)½

= 1/(82)½ = 1/8

7. Find the value of x for which 2x ÷ 2-4 = 45

Solution:

Given,

2x ÷ 2-4 = 45

Now, 2x × (½)-4 = (22)5

Or, 2x × (½)-4 = 210

Thus, 2x+4 = 210

⇒ x + 4 = 10

Hence, x + 4 = 10

So, x = 6

8. Calculate the missing value of “x” in the following expression: (11/9)3 × (9/11)6 = (11/9)2x-1

Solution:

Given,

(11/9)3 × (11/9)-6 = (11/9)2x-1

⇒ (11/9)3-6 = (11/9)2x-1

Therefore, -3 = 2x – 1
2x = -3 + 1
x = -2/2
x = 1

9. 5 books and 5 paper sheets are placed in a stack. Find the total thickness of the stack if each book has a thickness of 20 mm and each sheet has a thickness of 0.016 mm.

Solution:

Given,

Thickness of 1 book = 20 mm

And,

Thickness of one paper = 0.016 mm

So, thickness of 5 books = 20 x 5 = 100 mm

And,

Thickness of 5 papers = 0.016 × 5 = 0.08 mm

Now, the total thickness of a stack is:

= 100 + 0.08 = 100.08 mm

= 100.08 102 / 102 mm

= 1.008 × 102 mm

10. If a new-born bear weighs 4kg, calculate how many kilograms a five-year-old bear weigh if its weight increases by the power of 2 in 5 years ?

Solution:

Given,

Weight of new-born bear = 4 kg

Rate of weight increase in 5 years = power to 2

Thus, the weight of the 5-year old bear = 42 = 16 kg

Q.11: Simplify [25 x t-4]/[5-3 x 10 x t-8]

Solution:

We can write the given expression as;

[52x t-4]/[5-3 x 5 x 2 x t-8]

= [52 x t-4+8]/[5-3+1 x2]

= [52+2 x t4]/[2]

= [54 x t4]/[2]

= 625/2 t4

Q.12: Express 0.00000000837 in standard form.

Solution:

0.00000000837

= 0.00000000837 x 109 / 109

= 8.37 ×10-9

Q.13: Write 3.61492 x 10in usual form.

Solution: 3.61492 x 106

= 3.61492 x 1000000

= 3614920

Maths Class 8 Chapter 12 Extra Questions

  1. Evaluate: (-4)-3
  2. Simplify: (𝟑-7÷ 𝟑-9) × 𝟑-4
  3. Find the value of (37 + 4-3 + 53)0
  4. Evaluate: [{1/2}-1+{1/3}-1]-1
  5. Express 31860000000 in standard form.

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