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NCERT Exemplar · Class 7 · Maths

Chapter 11: Exponents and Powers

Practice each question, then open the answer or worked solution.

Questions

50 questions
Q11Written answer

In standard form, the number 72105.4 is written as 7.21054 × 10n where n is equal to

(a) 2 (b) 3 (c) 4 (d) 5

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Worked solution

Solution:-

(c) 4

Any number can be expressed as a decimal number between 1.0 and 10.0 (including 1.0) multiplied by a power of 10. Such form of a number is called its standard form or scientific notation.

72105.4 is written as 7.21054 × 104

Q12Written answer

Square of (-2/3) is

(a) -2/3 (b) 2/3 (c) -4/9 (d) 4/9

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Worked solution

Solution:-

(d) 4/9

Square of (-2/3) is = -22/32

= (-2 × -2)/(3 × 3)

= 4/9

Q13Written answer

cube of (-1/4) is

(a) -1/12 (b) 1/16 (c) -1/64 (d) 1/64

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Worked solution

Solution:-

(c) -1/64

Cube of (-1/4) is = -13/43

= (-1 × -1 × -1)/(4 × 4 × 4)

= -1/64

Q14Written answer

Which of the following is not equal to (-5/4)4?

(a) (-5)4/44 (b) 54/(-4)4

(c) –(54/44) (d) (-5/4) × (-5/4) × (-5/4) × (-5/4)

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Worked solution

Solution:-

(c) –(54/44)

Q15Written answer

Which of the following is not equal to 1 ?

(a) (23 × 33)/(4 × 18) (b) [(-2)3 × (-2)4] ÷ (-2)2

(c) (30 × 53)/(5 × 25) (d) 24/(70 + 30)3

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Worked solution

Solution:-

(d) 24/(70 + 30)3

= 24/(1 + 1)3

= 24/23

Q16Written answer

(2/3)3 × (5/7)3 is equal to

(a) ((2/3) × (5/7))9 (b) ((2/3) × (5/7))6

(c) ((2/3) × (5/7))3 (d) ((2/3) × (5/7))0

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Worked solution

Solution:-

(c) ((2/3) × (5/7))3

For any non-zero integers ‘a’ and ‘b’ and whole numbers m and n.

am × bm = (ab)m

Q17Written answer

In standard form, the number 829030000 is written as K × 108 where K is equal to (a) 82903 (b) 829.03 (c) 82.903 (d) 8.2903

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Worked solution

Solution:-

(d) 8.2903

Any number can be expressed as a decimal number between 1.0 and 10.0 (including 1.0) multiplied by a power of 10. Such form of a number is called its standard form or scientific notation.

829030000 is written as 8.2903 × 108

Q18Written answer

Which of the following has the largest value?

(a) 0.0001 (b) 1/10000 (c) 1/106 (d) (1/106) ÷ 0.1

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Worked solution

Solution:-

(a) 0.0001 and (b) 1/10000 = 0.0001

Q19Written answer

In standard form 72 crore is written as

(a) 72 × 107 (b) 72 × 108 (c) 7.2 × 108 (d) 7.2 × 107

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Worked solution

Solution:-

(c) 7.2 × 108

Any number can be expressed as a decimal number between 1.0 and 10.0 (including 1.0) multiplied by a power of 10. Such form of a number is called its standard form or scientific notation.

72 crore is written as = 72,00,00,000 = 7.2 × 108

Q20Written answer

For non-zero numbers a and b, (a/b)m ÷ (a/b)n, where m>n, is equal to

(a) (a/b)mn (b) (a/b)m + n (c) (a/b)m – n (d) ((a/b)m)n

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Worked solution

Solution:-

(c) (a/b)m – n

For any non-zero integers ‘a’ and ‘b’ and whole numbers m and n,

am ÷ an = am–n , m>n