S.chand publication New Learning Composite mathematics solution of class 8 Chapter 2 Exponents Exercise 2B

 Exercise 2B

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Q1 | Ex-2A |Class 8 |Exponents | S.Chand | New Learning | Composite maths | Chapter 2 | myhelper

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Question 1

Find each value

(a) 10^-4

Sol : 

$=\frac{1}{(10)^4}=\frac{1}{10000}$

(b) 10^-7

Sol : 

$=\frac{1}{(10)^7}=\frac{1}{10000000}$

(c) 10^-8

Sol :

$=\frac{1}{100000000}$

(d) 10^-10

Sol : 

$=\frac{1}{10000000000}$

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Q2 | Ex-2A |Class 8 |Exponents | S.Chand | New Learning | Composite maths | Chapter 2 | myhelper

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Question 2

Write each number in scientific notation.

(a) 5,700,000

Sol : 

=57×10⁵

=5.7×10⁶

(b) 8,19,000

Sol :

=819×10³

=8.19×10⁵

(c) 4,000,000,000

Sol :

=4×10^-9

(d) 56,000

Sol :

=56×10³

=5.6×10⁴

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Q3 | Ex-2A |Class 8 |Exponents | S.Chand | New Learning | Composite maths | Chapter 2 | myhelper

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Question 3

(a) 0.000053

Sol :

=53×10^-6

=5.3×10^-5

(b) 0.000000084

Sol :

=8.4×10^-9

=8.4×10^-8

(c) 0.0009

Sol :

=9×10^-4

(d) 0.0603

Sol :

=603×10^-4

=6.03×10^-2

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Q4 | Ex-2A |Class 8 |Exponents | S.Chand | New Learning | Composite maths | Chapter 2 | myhelper

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Question 4

Write each number in standard form.

(a) 5.7 x 10³

Sol :

$=\frac{57 \times 1000}{10}$

=5700

(b) 6.39 x 10⁵

Sol :

$=\frac{639 \times 100000}{100}$

=639000

(c) 1.71 x 10⁶

Sol :

$=\frac{171 \times {10}^6}{{10}^2}$

=1710000

(d) 4.0 x 10⁹

Sol :

$=4 \times {10}^{9}$

=4000000000

(e) 7.02 × 10⁴

Sol :

$=\frac{702 \times 10^4}{10^2}$

=70200

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Q5 | Ex-2A |Class 8 |Exponents | S.Chand | New Learning | Composite maths | Chapter 2 | myhelper

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Question 5

(a) 9.4 x 10^-4

Sol : 

$=\frac{94\times 10^{-4}}{10}$

=0.00094

(b) 2 x 10^-3

Sol : 

$=\frac{2}{1000}$

=0.002

(c) 5.01 x 10^-2

Sol : 

$=\frac{501\times 10^{-2}}{100}$

=0.0501

(d) 3.88 x 10^-1

Sol : 

$=\frac{388\times 10^{-1}}{10^2}$

=0.388

(e) 3.7×10^-9

Sol : 

$=\frac{37\times 10^{-9}}{10}$

=0.0000000037

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Q6 | Ex-2A |Class 8 |Exponents | S.Chand | New Learning | Composite maths | Chapter 2 | myhelper

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Question 6

Write the following facts in scientific notation.

(a) The distance from the earth to the sun is 149600000000 m.

Sol : 1.496×10¹¹ m

(b) the average diameter of a red blood cell is 0.000007 mm.

Sol : 7×10^-6 mm

(c) Diameter of a wire in a computer chip is 0.000003 m.

Sol : 3×10^-6 m

(d) Size of a plant cell is 0.00001275 m.

Sol : 1.275×10^-5 m