 # Important Questions Class 8 Maths Chapter 12 Exponents And Powers

Important questions for class 8 chapter 12- Exponents and Powers are given here which are crucial for CBSE class 8 exam. These extra class 8 maths questions from exponents and powers chapter cover some important short and long answer type questions with solutions.

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## 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.

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).

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

Or, -3 = 2x – 1

So, 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 = 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 = 42 = 16 kg.

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