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Exponents And Powers

Class 7th Mathematics NCERT Exemplar Solution
Exercise
  1. [(-3)^2]^3 is equal toA. (-3)^8 B. (-3)^6 C. (-3)^5 D. (-3)^23
  2. For a non-zero rational number x, x^8 ÷ x^2 is equal toA. x^4 B. x^6 C. x^10 D.…
  3. x is a non-zero rational number. Product of the square of x with the cube of x is…
  4. For any two non-zero rational numbers x and y, x^5 ÷ y^5 is equal toA. (x ÷ y)^1…
  5. am × an is equal toA. (a^2)mn B. am-n C. am + n D. amn
  6. (1^0 + 2^0 + 3^0) is equal toA. 0 B. 1 C. 3 D. 6
  7. Value of 10^22 + 10^20/10^20 isA. 10 B. 10^42 C. 101 D. 10^22
  8. The standard form of the number 12345 isA. 1234.5 × 10^1 B. 123.45 × 10^2 C.…
  9. If 2^1998 - 2^1997 - 2^1996 + 2^1995 = K.2^1995 , then the value of K isA. 1 B. 2…
  10. Which of the following is equal to 1?A. 2^0 + 3^0 + 4^0 B. 2^0 × 3^0 × 4^0 C.…
  11. In standard form, the number 72105.4 is written as 7.21054 × 10n where n is…
  12. Square of (-2/3) isA. -2/3 B. 2/3 C. -4/9 D. 4/9
  13. Cube of (-1/4) isA. -1/12 B. 1/16 C. -1/64 D. 1/64
  14. Which of the following is not equal to (-5/4)^4 ? A. (-5)^4/4^4 B. 5^4/(-4)^4 C.…
  15. Which of the following is not equal to 1?A. 2^3 x 3^2/4 x 18 B. [(-2)^3 x…
  16. (2/3)^3 x (5/7)^3 is equal toA. (2/3 x 5/7)^9 B. (2/3 x 5/7)^6 C. (2/3 x 5/7)^3…
  17. In standard form, the number 829030000 is written as K × 10^8 where K is equal…
  18. Which of the following has the largest value?A. 0.0001 B. 1/1000 C. 1/10^6 D.…
  19. In standard form 72 crore is written asA. 72 × 10^7 B. 72 × 10^8 C. 7.2 × 10^8…
  20. For non-zero numbers a and b, (a/b)^m / (a/b)^n where m n, is equal toA.…
  21. Which of the following is not true?A. 3^2 2^3 B. 4^3 = 2^6 C. 3^3 = 9 D. 2^5 5^2…
  22. Which power of 8 is equal to 2^6 ?A. 3 B. 2 C. 1 D. 4
  23. (-2)^31 × (-2)^13 = (-2) Fill in the blanks to make the statements true.…
  24. (-3)^8 ÷ (-3)^5 = (-3) Fill in the blanks to make the statements true.…
  25. (11/15)^4 x (arrow)^5 = (11/15)^9 Fill in the blanks to make the statements…
  26. (-1/4)^3 x (-1/4) - (-1/4)^11 Fill in the blanks to make the statements true.…
  27. [(7/11)^3]^4 = (7/11)^- Fill in the blanks to make the statements true.…
  28. (6/13)^10 / [(6/13)^5]^2 = (6/13) Fill in the blanks to make the statements…
  29. [(-1/4)^16]^2 = (-1/4) Fill in the blanks to make the statements true.…
  30. (13/14)^5 / (-)^2 = (13/14)^3 Fill in the blanks to make the statements true.…
  31. a^6 × a^5 × a^0 = a— Fill in the blanks to make the statements true.…
  32. 1 lakh = 10— Fill in the blanks to make the statements true.
  33. 1 million = 10— Fill in the blanks to make the statements true.
  34. 729 = 3— Fill in the blanks to make the statements true.
  35. 432 = 2^4 × 3— Fill in the blanks to make the statements true.
  36. 53700000 = ____ × 10^7 Fill in the blanks to make the statements true.…
  37. 88880000000 = --- × 10^10 Fill in the blanks to make the statements true.…
  38. 27500000 = 2.75 × 10— Fill in the blanks to make the statements true.…
  39. 340900000 = 3.409 × 10— Fill in the blanks to make the statements true.…
  40. Fill in the blanks with , or = sign. (a) 3^2 ______15 (b) 2^3 ______ 3^2 (c) 7^4…
  41. One million = 10^7 State whether the given statements are True or False.…
  42. One hour = 60^2 seconds State whether the given statements are True or False.…
  43. 1^0 × 0^1 = 1 State whether the given statements are True or False.…
  44. (-3)^4 = -12 State whether the given statements are True or False.…
  45. 3^4 4^3 State whether the given statements are True or False.
  46. (-3/5)^100 = (-3)^100/(-5)^100 State whether the given statements are True or…
  47. (10 + 10)^10 = 10^10 + 10^10 State whether the given statements are True or…
  48. x^0 × x^0 = x^0 ÷ x^0 is true for all non-zero values of x. State whether the…
  49. In the standard form, a large number can be expressed as a decimal number…
  50. 4^2 is greater than 2^4 . State whether the given statements are True or False.…
  51. xm + xm = x2m, where x is a non-zero rational number and m is a positive…
  52. xm × ym = (x × y)2m, where x and y are non-zero rational numbers and m is a…
  53. xm ÷ ym = (x ÷ y)m, where x and y are non-zero rational numbers and m is a…
  54. xm × xn = xm + n, where x is a non-zero rational number and m,n are positive…
  55. 4^9 is greater than 16^3 . State whether the given statements are True or False.…
  56. (2/5)^3 / (5/2)^3 = 1 State whether the given statements are True or False.…
  57. (4/3)^5 x (5/7)^5 = (4/3 + 5/7)^5 State whether the given statements are True or…
  58. (5/8)^9 / (5/8)^4 = (5/8)^4 State whether the given statements are True or…
  59. (7/3)^2 x (7/3)^5 = (7/3)^10 State whether the given statements are True or…
  60. 5^0 × 25^0 × 125^0 = (5^0)^6 State whether the given statements are True or…
  61. 876543 = 8 × 10^5 + 7 × 10^4 + 6 × 10^3 + 5 × 10^2 + 4 × 10^1 + 3 × 10^0 State…
  62. 600060 = 6 × 10^5 + 6 × 10^2 State whether the given statements are True or…
  63. 4 × 10^5 + 3 × 10^4 + 2 × 10^3 + 1 × 10^0 = 432010 State whether the given…
  64. 8 × 10^6 + 2 × 10^4 + 5 × 10^2 + 9 × 10^0 = 8020509 State whether the given…
  65. 4^0 + 5^0 + 6^0 = (4 + 5 + 6)^0 State whether the given statements are True or…
  66. Arrange in ascending order: 2^5 , 3^3 , 2^3 ×2, (3^3)^2 , 3^5 , 4^0 , 2^3 ×3^1…
  67. Arrange in descending order: 22 + 3, (2^2)^3 , 2 × 2^2 , 3^5/3^2 3^2 × 3^0 , 2^3…
  68. By what number should (- 4)^5 be divided so that the quotient may be equal to (-…
  69. Find m so that (2/9)^3 x (2/9)^6 = (2/9)^2m-1
  70. If p/q = (3/2)^2 / (9/4)^0 find the value of (p/q)^3
  71. Find the reciprocal of the rational number (1/2)^2 / (2/3)^3
  72. Find the value of: (a) 7^0 (b) 7^7 ÷ 7^7 (c) (-7)2 × 7 - 6 - 8 (d) (2^0 + 3^0 +…
  73. Find the value of n, where n is an integer and 2^n-5 x 6^2n-4 = 1/12^4 x 2…
  74. Express the following in usual form: (a) 8.01 × 10^7 (b) 1.75 × 10-3…
  75. Find the value of (a) 2^5 (b) (-3^5) (c) -(-4)^4
  76. Express the following in exponential form: (a) 3 × 3 × 3 × a × a × a ×a (b) a ×…
  77. How many times of 30 must be added together to get a sum equal to 30^7 ?…
  78. Express each of the following numbers using exponential notations: (a) 1024 (b)…
  79. Identify the greater number, in each of the following: (a) 2^6 or 6^2 (b) 2^9 or…
  80. Express each of the following as a product of powers of their prime factors: (a)…
  81. Express each of the following in single exponential form: (a) 2^3 × 3^3 (b) 2^4…
  82. 76, 47, 000 Express the following numbers in standard form:
  83. 8, 19, 00, 000 Express the following numbers in standard form:
  84. 5, 83, 00, 00, 00, 000 Express the following numbers in standard form:…
  85. 24 billion Express the following numbers in standard form:
  86. The speed of light in vaccum is 3 × 10^8 m/s. Sunlight takes about 8 minutes to…
  87. [(3/7)^4 x (3/7)^5] / (3/7)^7 Simplify and express each of the following in…
  88. Simplify and express each of the following in exponential form: [(7/11)^5 /…
  89. (3^7 / 3^5)^4 Simplify and express each of the following in exponential form:…
  90. (a^6/a^4) x a^5 x a^0 Simplify and express each of the following in exponential…
  91. [(3/5)^3 x (3/5)^8] / [(3/5)^2 x (3/5)^4] Simplify and express each of the…
  92. (5^15 / 5^10) x 5^5 Simplify and express each of the following in exponential…
  93. 7^8 x a^10b^7c^12/7^6 x a^8b^4c^12 Evaluate
  94. 5^4 x 7^4 x 2^7/8 x 49 x 5^3 Evaluate
  95. 125 x 5^2 x a^7/10^3 x a^4 Evaluate
  96. 3^4 x 12^3 x 36/2^5 x 6^3 Evaluate
  97. (6 x 10/2^2 x 5^3)^2 x 25/27 Evaluate
  98. 15^4 x 18^3/3^3 x 5^2 x 12^2 Evaluate
  99. 6^4 x 9^2 x 25^3/3^2 x 4^2 x 15^6 Evaluate
  100. Express the given information in Scientific notation (standard form) and then…
  101. Express the given information in Scientific notation and then arrange them in…
  102. Write the number of seconds in scientific notation.
  103. In our own planet Earth, 361,419,000 square kilometre of area is covered with…
  104. If 2n + 2 - 2n + 1 + 2n = c × 2n, find the value of c.
  105. A light year is the distance that light can travel in one year. 1 light year =…
  106. Geometry Application : The number of diagonals of an n-sided figure is 1/2 (n^2…
  107. Life Science : Bacteria can divide in every 20 minutes. So 1 bacterium can…
  108. Blubber makes up 27 per cent of a blue whale’s body weight. Deepak found the…
  109. Life Science Application : The major components of human blood are red blood…
  110. A googol is the number 1 followed by 100 zeroes. (a) How is a googol written as…
  111. What’s the error? A student said that 3^5/9^5 is the same as 1/3 what mistake…

Exercise
Question 1.

[(–3)2]3 is equal to
A. (–3)8

B. (–3)6

C. (–3)5

D. (–3)23


Answer:

According to the law of indices:

(am)n = a(m × n)


Applying the same law here,


In the above question,


a = -3


m = 2


n = 3


∴ m × n = 2 × 3


= 6


[(–3)2]3 = (–3)6


So correct answer is B.


Question 2.

For a non-zero rational number x, x8 ÷ x2 is equal to
A. x4

B. x6

C. x10

D. x16


Answer:

Again we have another law of indices which is as follows:

am ÷ an = a (m-n)


Here in the question,


a = x


m = 8


n = 2


∴ m – n = 8 – 2


= 6


x8 ÷ x2 = x6


So the correct answer is B.


Question 3.

x is a non-zero rational number. Product of the square of x with the cube of x is equal to the
A. second power of x

B. third power of x

C. fifth power of x

D. sixth power of x


Answer:

Let us break the question,

Square of x = x2


Cube of x = x3


According to Law of indices,


am × an = a (m + n)


Here in the question,


a = x


m = 2


n = 3


∴ m + n = 3 + 2


= 5


x2 × x3 = x5


So the correct answer is C.


Question 4.

For any two non-zero rational numbers x and y, x5 ÷ y5 is equal to
A. (x ÷ y)1

B. (x ÷ y)0

C. (x ÷ y)5

D. (x ÷ y)10


Answer:

According to Law of Indices,


Here in the question,


a = x


b = y


m = 5


So by the Law of Indices,


x5 ÷ y5 = (x ÷ y)5


So the correct answer is C.


Question 5.

am × an is equal to
A. (a2)mn

B. am–n

C. am + n

D. amn


Answer:

According to Law of indices,

am × an = a (m + n)


So the correct answer is C.


Question 6.

(10 + 20 + 30) is equal to
A. 0

B. 1

C. 3

D. 6


Answer:

We have the law of Indices as follows:

a0 = 1


Where a = any integer


(10 + 20 + 30) = 1 + 1 + 1


= 3


So the correct answer is C.


Question 7.

Value of is
A. 10

B. 1042

C. 101

D. 1022


Answer:

The above question can be written as follows:


Again we have another law of indices which is as follows:


am ÷ an = a (m-n)


Here in the question,


For first part,


a = 10


m = 22


n = 20


∴ m – n = 22 – 20


= 2


For second part,


a = 10


m = 20


n = 20


∴ m – n = 20 – 20


= 0




We have the law of Indices as follows:


a0 = 1


Where a = any integer




So the correct answer is C.


Question 8.

The standard form of the number 12345 is
A. 1234.5 × 101

B. 123.45 × 102

C. 12.345 × 103

D. 1.2345 × 104


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 12345,


Here only one number will be kept before decimal point that is 1.



12345 = 1.2345 × 104


So the correct answer is D.


Question 9.

If 21998 – 21997 – 21996 + 21995 = K.21995, then the value of K is
A. 1

B. 2

C. 3

D. 4


Answer:

21998 – 21997 – 21996 + 21995 = K.21995

The above question can be written as follows:



For first part,


a = 2


m = 1998


n = 1995


∴ m – n = 1998 - 1995


= 3


For second part,


a = 2


m = 1997


n = 1995


∴ m – n = 1997 – 1995


= 2


For third part,


a = 2


m = 1996


n = 1995


∴ m – n = 1996 - 1995


= 1


For second part,


a = 2


m = 1995


n = 1995


∴ m – n = 1995 – 1995


= 0




k = 8 - 4 – 2 + 1


k = 3


So the correct answer is C.


Question 10.

Which of the following is equal to 1?
A. 20 + 30 + 40

B. 20 × 30 × 40

C. (30 – 20) × 40

D. (30 – 20) × (30 + 20)


Answer:

We have the law of Indices as follows:

a0 = 1


Where a = any integer


Let us try option A.


20 + 30 + 40 = 1 + 1 + 1


= 3


20 × 30 × 40 = 1 × 1 × 1


= 1


(30 – 20) × 40 = (1-1) × 1


= 0 × 1


= 0


(30 – 20) × (30 + 20) = (1-1) × (1 + 1)


= 0 × 1


= 0


So the correct answer is B.


Question 11.

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


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 72105.4,


Here only one number will be kept before decimal point that is 7.


Number of terms to be shifted after decimal point = 4



72105.4 = 7.21054 × 104


So n = 4


So the correct answer is C.


Question 12.

Square of is
A.

B.

C.

D.


Answer:




So the correct answer is D.


Question 13.

Cube of is
A.

B.

C.

D.


Answer:




So the correct answer is C.


Question 14.

Which of the following is not equal to
A.

B.

C.

D.


Answer:


Any negative number when raised to a power which is an even number, the result obtained is positive power of that number.


Any negative number when raised to a power which is an add number, the result obtained is negative power of that number.


So since in the question, the power is 4, the result of (-5)4 will be positive 4th power of 5.


So the answer will be positive.


By looking at the option, Option C does not match to the desired result as the negative sign will persist in the result making it negative.




So option C does not match with the result.


So correct answer is C.


Question 15.

Which of the following is not equal to 1?
A.

B.

C.

D.


Answer:

Let us solve each option,

For option A,





For option B,


Again we have another law of indices which is as follows:


am ÷ an = a (m-n)


According to Law of indices,


am × an = a (m + n)





For option C,




For Option D,






So the correct answer is D.


Question 16.

is equal to
A.

B.

C.

D.


Answer:

According to law of indices:

am × bm = (ab)m


Here in the question,


a = 2/3


b = 5/7


m = 3



So the correct answer is C.


Question 17.

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


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 829030000,


Here only one number will be kept before decimal point that is 8.


Number of terms to be shifted after decimal point = 8



829030000 = 8.2903 × 104


So the correct answer is D.


Question 18.

Which of the following has the largest value?
A. 0.0001

B.

C.

D.


Answer:

The options C and D results in very low values.

The option B = 0.001


Option A is = 0.0001


So after seeing all the options, option B has highest value.


So the correct answer is B.


Question 19.

In standard form 72 crore is written as
A. 72 × 107

B. 72 × 108

C. 7.2 × 108

D. 7.2 × 107


Answer:

Let us first understand the number of zeroes in a crore,

One lakh = 1, 00,000


Number of zeroes = 5


Ten Lakhs = 10, 00, 000


Number of zeroes = 6


One crore = 1, 00, 00, 000


Number of zeroes = 7


Ten crore = 10, 00, 00, 000


Number of zeroes = 8


Therefore 72 crore = 72, 00, 00, 000


Number of zeroes = 7


Number of terms to be shifted after decimal point = 8



72, 00, 00, 000 = 7.2 × 108


So the correct answer is C.


Question 20.

For non-zero numbers a and b, where m > n, is equal to
A.

B.

C.

D.


Answer:

Again we have another law of indices which is as follows:

am ÷ an = a (m-n)


Here in the question,


Here a = a/b


Therefore, by the law of indices:



So the correct answer is C.


Question 21.

Which of the following is not true?
A. 32 > 23

B. 43 = 26

C. 33 = 9

D. 25 > 52


Answer:

Let us evaluate each option,

For option A,


32>23


9>8


This is true.


For option B,


43>26


64 = 64


This is also true.


For option C,


33 = 9


27 = 9


This is false.


For option D,


25>52


32>25


This is also true.


So the correct answer is C.


Question 22.

Which power of 8 is equal to 26?
A. 3

B. 2

C. 1

D. 4


Answer:

26 = 64

We know that square of 8 = 64


Therefore second power of 8 is equal to 26.


So the correct answer is B.


Question 23.

Fill in the blanks to make the statements true.

(–2)31 × (–2)13 = (–2)


Answer:

According to Law of indices,

am × an = a (m + n)


Here in the question,


a = -2


m = 31


n = 13


∴ m + n = 31 + 13


= 44


(-2)31 × (-2)13 = (-2)44



Question 24.

Fill in the blanks to make the statements true.

(–3)8 ÷ (–3)5 = (–3)


Answer:

Again we have another law of indices which is as follows:

am ÷ an = a (m-n)


Here in the question,


a = -3


m = 8


n = 5


∴ m – n = 8 – 5


= 3


(-3)8 ÷ (-3)5 = (-3)3



Question 25.

Fill in the blanks to make the statements true.



Answer:

According to Law of indices,

am × an = a (m + n)


Here in the question,



We will have to multiply (11/15)5 with (11/15)4 to get (11/15)9



Therefore the answer for the fill in the blanks = 11/15



Question 26.

Fill in the blanks to make the statements true.



Answer:

According to Law of indices,

am × an = a (m + n)


a = -1/4


m = 3


m + n = 11


∴ n = 8


Here in the question,



We will have to multiply (-1/4)8 with (-1/4)3 to get (-1/4)11



Therefore the answer for the fill in the blanks = 8



Question 27.

Fill in the blanks to make the statements true.



Answer:

According to the law of indices:

(am)n = a(m × n)


Applying the same law here,


In the above question,


a = 7/11


m = 3


n = 4


∴ m × n = 3 × 4


= 12


[(7/11)3]4 = (7/11)12



Question 28.

Fill in the blanks to make the statements true.



Answer:

According to the law of indices:

(am)n = a(m × n)


Applying the same law here,


In the above question,


a = 6/13


m = 5


n = 2


∴ m × n = 5 × 2


= 10


[(6/13)5]2 = (6/13)10


Again we have another law of indices which is as follows:


am ÷ an = a (m-n)


Here in the question,


a = 6/13


m = 10


n = 10


∴ m – n = 10 - 10


= 0


(6/13)10 ÷ (6/13)10 = (6/13)0



Question 29.

Fill in the blanks to make the statements true.



Answer:

According to the law of indices:

(am)n = a(m × n)


Applying the same law here,


In the above question,


a = -1/4


m = 16


n = 2


∴ m × n = 16 × 2


= 32


[(-1/4)16]2 = (-1/4)32



Question 30.

Fill in the blanks to make the statements true.



Answer:

According to Law of indices,

am ÷ an = a (m - n)


Here in the question,



We will have to divide (13/14)5 by (13/14)2 to get (13/14)3



Therefore the answer for the fill in the blanks = 13/14



Question 31.

Fill in the blanks to make the statements true.

a6 × a5 × a0 = a


Answer:

According to Law of indices,

am × an = a (m + n)


m = 6


n = 5


∴ m + n = 5 + 6


= 11


We have the law of Indices as follows:


a0 = 1


Where a = any integer


a6 × a5 × a0 = a11 × 1


= a11


Therefore the answer for the fill in the blanks = 11



Question 32.

Fill in the blanks to make the statements true.

1 lakh = 10


Answer:

The power of ten represent the number of zeroes in 1 lakh.

So we know 1 lakh = 1, 00, 000


So total number of zeroes in 1 lakh = 5


1 lakh = 105


Therefore the answer for the fill in the blanks = 5



Question 33.

Fill in the blanks to make the statements true.

1 million = 10


Answer:

The power of ten represent the number of zeroes in 1 million.

So we know 1 million = 1, 000, 000


So total number of zeroes in 1 million = 6


1 million = 106


Therefore the answer for the fill in the blanks = 6



Question 34.

Fill in the blanks to make the statements true.

729 = 3


Answer:

We know that 729 is the cube of 9

729 = 93


We also know that square of 3 = 9


So 729 = (32)3


According to the law of indices:


(am)n = a(m × n)


Applying the same law here,


In the above question,


a = 3


m = 2


n = 3


∴ m × n = 2 × 3


= 6


So 729 = 36


Therefore the answer for the fill in the blanks = 6



Question 35.

Fill in the blanks to make the statements true.

432 = 24 × 3


Answer:

24 = 2 × 2 × 2 × 2


= 4 × 4


= 16


So when 432 / 16 we get = 27


27 = 3 × 3 × 3


= 33


So 432 = 24 × 33


Therefore the answer for the fill in the blanks = 3



Question 36.

Fill in the blanks to make the statements true.

53700000 = ____ × 107


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 53700000,


Here only one number will be kept before decimal point that is 5.


Number of terms to be shifted after decimal point = 7



53700000 = 5.37 × 107


Therefore the answer for the fill in the blanks = 5.37



Question 37.

Fill in the blanks to make the statements true.

88880000000 = ––– × 1010


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 88880000000,


Here only one number will be kept before decimal point that is 8.


Number of terms to be shifted after decimal point = 10



88880000000 = 8.888 × 1010


Therefore the answer for the fill in the blanks = 8.888



Question 38.

Fill in the blanks to make the statements true.

27500000 = 2.75 × 10


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 27500000,


Here only one number will be kept before decimal point that is 2.


Number of terms to be shifted after decimal point = 7



27500000 = 2.75 × 107


Therefore the answer for the fill in the blanks = 7



Question 39.

Fill in the blanks to make the statements true.

340900000 = 3.409 × 10


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 340900000,


Here only one number will be kept before decimal point that is 3.


Number of terms to be shifted after decimal point = 8



340900000 = 3.409× 108


Therefore the answer for the fill in the blanks = 8



Question 40.

Fill in the blanks with <, > or = sign.

(a) 32 ______15

(b) 23 ______ 32

(c) 74 ______54

(d) 10,000 ______ 105

(e) 63 _____44


Answer:

(a) We know that 32 = 3 × 3


= 9


So 9 < 15


Therefore the answer for the fill in the blanks = <


(b) We know that 32 = 3 × 3


= 9


We also know that 23 = 2 × 2 × 2


= 8


So 8 < 9


Therefore the answer for the fill in the blanks = <


(c) We know that 74 = 7 × 7 × 7 × 7


= 49 × 49


= 2401


We also know that 54 = 5 × 5 × 5 × 5


= 25 × 25


= 625


So 2401 > 625


Therefore the answer for the fill in the blanks = >


(d) The power of 10 represent the number of zeroes accompanying 10.


So 105 = 1, 00,000


10,000 < 105


Therefore the answer for the fill in the blanks = <


(e) We know that 63 = 6 × 6 × 6


= 6 × 36


= 216


We also know that 44 = 4 × 4 × 4 × 4


= 16 × 16


= 256


So 216 < 256


Therefore the answer for the fill in the blanks = <



Question 41.

State whether the given statements are True or False.

One million = 107


Answer:

The power of 10 represent the number of zeroes accompanying 10.

So 107 = 10, 000,000


But one million = 1, 000,000


So 1 million is not equal to 107


So the statement is false.



Question 42.

State whether the given statements are True or False.

One hour = 602 seconds


Answer:

We know that,

1 hour = 60 minutes


1 minute = 60 seconds


∴ 1 hour = 60 × 60 seconds


= 602 seconds


Therefore the statement is true.



Question 43.

State whether the given statements are True or False.

10 × 01 = 1


Answer:

We have the law of Indices as follows:

a0 = 1


Where a = any integer


Therefore 10 = 1


Zero raise to any number is zero.


10 × 01 = 1 × 0


= 0


So the statement is false.



Question 44.

State whether the given statements are True or False.

(–3)4 = –12


Answer:

Let us first solve LHS,

(–3)4 = (-3) × (-3) × (-3) × (-3)


= 9 × 9


= 81


So the statement is false.



Question 45.

State whether the given statements are True or False.

34 > 43


Answer:

We know that 33 = 3 × 3 × 3

= 3 × 9


= 27


We also know that 43 = 4 × 4 × 4


= 16 × 4


= 64


So 27 < 64


So the given statement is false.



Question 46.

State whether the given statements are True or False.



Answer:


Any negative number when raised to a power which is an even number, the result obtained is positive power of that number.


Any negative number when raised to a power which is an add number, the result obtained is negative power of that number.


So since in the RHS, the power is 100, the result of (-5)100 will be positive 100th power of 5.


Hence RHS is equal to LHS


So the statement is true.



Question 47.

State whether the given statements are True or False.

(10 + 10)10 = 1010 + 1010


Answer:

Let us solve LHS,

(10 + 10)10 = (20)10


Hence LHS is not equal to RHS


So the statement is false.



Question 48.

State whether the given statements are True or False.

x0 × x0 = x0 ÷ x0 is true for all non-zero values of x.


Answer:

Again we have another law of indices which is as follows:

am ÷ an = a (m-n)


Here in the question,


a = x


m = 0


n = 0


∴ m – n = 0 – 0


= 0


x0 ÷ x0 = x0


According to Law of indices,


am × an = a (m + n)


Here in the question,


a = x


m = 0


n = 0


∴ m + n = 0 + 0


= 0


x0 × x0 = x0


So the result obtained in both the question is same.


Hence statement is true.



Question 49.

State whether the given statements are True or False.

In the standard form, a large number can be expressed as a decimal number between 0 and 1, multiplied by a power of 10.


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


A number in standard form is represented as a × 10k where a lies in the range of 1 to 10.


So the statement is false.



Question 50.

State whether the given statements are True or False.

42 is greater than 24.


Answer:

We know that 42 = 4 × 4

= 16


We also know that 24 = 2 × 2 × 2 × 2


= 4 × 4


= 16


So 42 is not greater than 24 rather they are equal.


So the statement is false.



Question 51.

State whether the given statements are True or False.

xm + xm = x2m, where x is a non-zero rational number and m is a positive integer.


Answer:

xm + xm = 2 xm

The Law of Indices for powers holds only for multiplication when both the bases are same.


So the statement is false.



Question 52.

State whether the given statements are True or False.

xm × ym = (x × y)2m, where x and y are non-zero rational numbers and m is a positive integer.


Answer:

According to law of indices:

am × bm = (ab)m


Here in the question,


a = x


b = y


xm × ym = (x × y)m


So the statement is false.



Question 53.

State whether the given statements are True or False.

xm ÷ ym = (x ÷ y)m, where x and y are non-zero rational numbers and m is a positive integer.


Answer:

According to law of indices:

am ÷ bm = (a ÷ b)m


Here in the question,


a = x


b = y


xm ÷ ym = (x ÷ y)m


So the statement is true.



Question 54.

State whether the given statements are True or False.

xm × xn = xm + n, where x is a non-zero rational number and m,n are positive integers.


Answer:

According to Law of indices,

am × an = a (m + n)


xm × xn = xm + n


So the statement is true.



Question 55.

State whether the given statements are True or False.

49 is greater than 163.


Answer:

We know that 163 = 16 × 16 × 16

= 256 × 16


= 4096


We also know that 49 = 4 × 4 × 4 × 4 × 4 × 4 × 4 × 4 × 4


= 16 ×16 × 16 × 64


= 2, 62, 144


So 49 is greater than 163.


So the statement is true.



Question 56.

State whether the given statements are True or False.



Answer:

According to law of indices:

am ÷ bm = (a ÷ b)m


Here in the question,


a = 2 / 5


b = 5 / 2





So the statement is false.



Question 57.

State whether the given statements are True or False.



Answer:

According to law of indices:

am × bm = (ab)m


Here in the question,


a = 4 / 3


b = 5 / 7


So In the RHS (4/3) has to be multiplied with (5/7) and not added.



So the statement is false.



Question 58.

State whether the given statements are True or False.



Answer:

According to Law of indices,

am ÷ an = a (m - n)


Here in the question,


a = 5/8


m = 9


n = 4


m – n = 9 – 4


= 5



So the statement is false.



Question 59.

State whether the given statements are True or False.



Answer:

According to Law of indices,

am × an = a (m + n)


Here in the question,


a = 7/3


m = 2


n = 5


m – n = 2 + 5


= 7



So the statement is false.



Question 60.

State whether the given statements are True or False.

50 × 250 × 1250 = (50)6


Answer:

250 = (52)0

1250 = (53)0


50 = (51)0


50 × 250 × 1250 = (51 × 52 × 53)0


= (56)0


(56)0 is same as (50)6


So the statement is true.



Question 61.

State whether the given statements are True or False.

876543 = 8 × 105 + 7 × 104 + 6 × 103 + 5 × 102 + 4 × 101 + 3 × 100


Answer:

Let us add all the terms:

(8 × 1, 00,000) + (7 × 10,000) + (6 × 1000) + (5× 100) + (4 × 10) + 3


⟹ 8, 00,000 + 70,000 + 6000 + 500 + 40 + 3


⟹ 876543


So the statement is true.



Question 62.

State whether the given statements are True or False.

600060 = 6 × 105 + 6 × 102


Answer:

Let us add the terms on RHS,

⟹ (6 × 1, 00,000) + (6× 100)


⟹ 6, 00,000 + 600


⟹ 6, 00, 600


So LHS is not equal to RHS.


So the statement is false.



Question 63.

State whether the given statements are True or False.

4 × 105 + 3 × 104 + 2 × 103 + 1 × 100 = 432010


Answer:

Let us add the terms on LHS:

⟹ (4 × 1, 00,000) + (3 × 10,000) + (2 × 1000) + 1


⟹ 4, 00,000 + 30,000 + 2000 + 1


⟹ 4, 32, 001


So LHS is not equal to RHS.


So the statement is false.



Question 64.

State whether the given statements are True or False.

8 × 106 + 2 × 104 + 5 × 102 + 9 × 100 = 8020509


Answer:

Let us add the terms on LHS:

⟹ (8 × 10, 00,000) + (2 × 10,000) + (5 × 100) + 9


⟹ 80, 00,000 + 20,000 + 500 + 9


⟹ 80, 20, 509


So LHS is equal to RHS.


So the statement is true.



Question 65.

State whether the given statements are True or False.

40 + 50 + 60 = (4 + 5 + 6)0


Answer:

We have the law of Indices as follows:

a0 = 1


Where a = any integer


40 + 50 + 60 = 1 + 1 + 1


= 3


(4 + 5 + 6)0 = (15)0


= 1


So LHS is not equal to RHS.


So the statement is false.



Question 66.

Arrange in ascending order:

25, 33, 23×2, (33)2, 35, 40, 23×31


Answer:

Let us simplify each term,

25 = 4 × 4 × 2


= 16 × 2


= 32


33 = 3 × 3 × 3


= 27


23×2 = 2 × 2 × 2 × 2


= 16


(33)2 = 33×2


= 36


= 729


35 = 3 × 3 × 3 × 3 × 3


= 243


40 = 1


23×3 = 2 × 2 × 2 × 3


= 24


So the ascending order is as follows:


1, 16, 24, 27, 32, 243, 729



Question 67.

Arrange in descending order:

22 + 3, (22)3, 2 × 22, 32 × 30, 23 × 52


Answer:

Let us simplify each term,

22 + 3 = 25 = 4 × 4 × 2


= 16 × 2


= 32


(22)3 = (22 × 3)


= 26


= 64


22×2 = 2 × 2 × 2


= 8


(35) / (32) = 33


= 3 × 3 × 3


= 27


32 × 30 = 9 × 1


= 9


23 × 52 = 8 × 25


= 200


So the ascending order is as follows:


200, 64, 32, 27, 9, 8



Question 68.

By what number should (– 4)5 be divided so that the quotient may be equal to (– 4)3?


Answer:

According to Law of indices,

am ÷ an = a (m - n)


Here in the question,



We will have to divide (-4)5 by (-4)2 to get (-4)3




Question 69.

Find m so that


Answer:

According to Law of indices,

ax × ay = a (x + y)


Here in the question,


a = 2/9


x = 3


y = 6


∴ x + y = 3 + 6


= 9


2m – 1 = 9


2m = 10


m = 5



Question 70.

If find the value of


Answer:











Question 71.

Find the reciprocal of the rational number


Answer:





Reciprocal of the rational number = 32 / 27



Question 72.

Find the value of:

(a) 70

(b) 77 ÷ 77

(c) (–7)2 × 7 – 6 – 8

(d) (20 + 30 + 40) (40 – 30 – 20)

(e) 2 × 3 × 4 ÷ 20 × 30 × 40

(f) (80 – 20) × (80 + 20)


Answer:

(a) We have the law of Indices as follows:


a0 = 1


Where a = any integer


70 = 1


(b) According to Law of indices,


ax ÷ ay = a (x - y)


Here in the question,


a = 7


x = 7


y = 7


∴ x - y = 7 - 7


= 0


77 ÷ 77 = 70 = 1


(c) (–7)2 × 7 – 6 – 8

= (–7)14-14


= (–7)0


= 1


(d) (20 + 30 + 40) (40 – 30 – 20) = (1 + 1 + 1) × (1-1-1)


= 3 × -1


= -3


(e) Let us evaluate the terms separately,


2 × 3 × 4 = 6 × 4


= 24


20 × 30 × 40 = 1 × 1 × 1


= 1


2 × 3 × 4 ÷ 20 × 30 × 40 = 24 / 1


= 24


(f) (80 – 20) × (80 + 20)

= (1 – 1) × (1 + 1)


= 0 × 1


= 0


Question 73.

Find the value of n, where n is an integer and


Answer:





………………….


According to law of indices:


am × bm = (ab)m




Now comparing on both sides


2n-5 = 2-5


n-5 = -5


n = 0


62n-4 = 6-4


2n-4 = -4


2n = -4 + 4


2n = 0


n = 0



Question 74.

Express the following in usual form:

(a) 8.01 × 107

(b) 1.75 × 10–3


Answer:

(a) For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The positive power of 10 denotes the number of terms shifted after the decimal point.


8.01 × 107 = 8, 01, 00, 000


(b) For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.


The positive power of 10 denotes the number of terms shifted after the decimal point.


1.75 × 10–3 = 0.00175



Question 75.

Find the value of

(a) 25

(b) (-35)

(c) -(-4)4


Answer:

(a) 25 = 2 × 2 × 2 × 2 × 2

= 4 × 4 × 2


= 16 × 2


= 32


(b) (-3)5 = (-3) × (-3) × (-3) × (-3) × (-3)


= 9 × 9 × (-3)


= 81 × -3


= -243


(c) - (-4)4 = - [(-4) × (-4) × (-4) × (-4)]


= - [16 × 16]


= - 256



Question 76.

Express the following in exponential form:

(a) 3 × 3 × 3 × a × a × a ×a

(b) a × a × b × b × b × c × c × c × c

(c) s × s × t × t × s × s × t


Answer:

(a) Number of terms of 3 = 3


Number of terms of a = 4


3 × 3 × 3 × a × a × a ×a = 33a4


(b) Number of terms of a = 2


Number of terms of b = 3


Number of terms of c = 4


a × a × b × b × b × c × c × c × c = a2b3c4


(c) Number of terms of s = 4


Number of terms of t = 3


s × s × t × t × s × s × t = s4t3


Question 77.

How many times of 30 must be added together to get a sum equal to 307?


Answer:

Number of times 30 should be added = 307 / 30

= 306


To understand the above method,


Take example of 24


24 = 16


But when we add 2 eight times we get 16 [16 / 2].



Question 78.

Express each of the following numbers using exponential notations:

(a) 1024

(b) 1029

(c)


Answer:

(a) 1024 = 32 × 32

= 25 × 25


= 210


(b) 1029 = 32 × 32 + 51


= 25 × 25 + 51


= 210 + 51


(c)





Question 79.

Identify the greater number, in each of the following:

(a) 26 or 62

(b) 29 or 92

(c) 7.9 × 104 or 5.28 × 105


Answer:

(a) Let us find the values of each term,

26 = 2 × 2 × 2 × 2 × 2 × 2


= 4 × 4 × 4


= 64


62 = 36


So 26 is greater.


(b) 29 = 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2


= 8 × 8 × 8


= 512


92 = 81


So 29 is greater.


(c) 7.9 × 104 = 79, 000


5.28 × 105 = 5, 28, 000


So it is clearly seen that 5.28 × 105 is greater



Question 80.

Express each of the following as a product of powers of their prime factors:

(a) 9000

(b) 2025

(c) 800


Answer:

(a) 9000 = 5 × 5 × 5 × 3 × 3 × 2 × 2 × 2


9000 = 53 × 32 × 23


(b) 2025 = 5 × 5 × 3 × 3 ×3 × 3


2025 = 52 × 34


(c) 800 = 2 × 2 × 2 × 10 × 10


800 = 2 × 2 × 2 × 5 × 2 × 5 × 2


800 = 25 × 52



Question 81.

Express each of the following in single exponential form:

(a) 23 × 33

(b) 24 × 42

(c) 52 × 72

(d) (– 5)5 × (–5)

(e) (– 3)3 × (– 10)3

(f) (– 11)2 × (– 2)2


Answer:

(a) According to law of indices:


am × bm = (ab)m


Here in the question,


23 × 33 = (3 × 2)3


= 63


(b) 23 = 2 × 2 × 2 × 2


= 16


42 = 16


24 × 42 = 16 × 16


= 162


(c) According to law of indices:


am × bm = (ab)m


Here in the question,


52 = 25


72 = 49


52 × 72 = (5 × 7)2


= 352


(d) (– 5)5 × (–5) = (– 5)5 + 1


= (– 5)6


(e) According to law of indices:


am × bm = (ab)m


Here in the question,


(– 3)3 × (– 10)3 = (-3 × -10)3


= (30)3


(f) According to law of indices:


am × bm = (ab)m


Here in the question,


(– 11)2 × (– 2)2 = (-11 × -2)2


= 222



Question 82.

Express the following numbers in standard form:

76, 47, 000


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 76, 47, 000,


Here only one number will be kept before decimal point that is 7.


Number of terms to be shifted after decimal point = 6



76, 47, 000 = 7.647 × 106



Question 83.

Express the following numbers in standard form:

8, 19, 00, 000


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 8, 19, 00, 000,


Here only one number will be kept before decimal point that is 8.


Number of terms to be shifted after decimal point = 7



8, 19, 00, 000 = 8.19 × 107



Question 84.

Express the following numbers in standard form:

5, 83, 00, 00, 00, 000


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 5, 83, 00, 00, 00, 000,


Here only one number will be kept before decimal point that is 5.


Number of terms to be shifted after decimal point = 11



5, 83, 00, 00, 00, 000 = 5.83 × 1011



Question 85.

Express the following numbers in standard form:

24 billion


Answer:

For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 24 billion = 24,000,000,000


Here only one number will be kept before decimal point that is 2.


Number of terms to be shifted after decimal point = 10



24,000,000,000 = 2.4 × 1010



Question 86.

The speed of light in vaccum is 3 × 108 m/s. Sunlight takes about 8 minutes to reach the earth. Express distance of Sun from Earth in standard form.


Answer:

Given:

Speed of light = 3 × 108 m/s


Time Taken = 8 minutes


= 8 × 60


= 480 seconds


Speed = Distance / Time


Distance = Speed × Time


Distance = (3 × 108) × (480)


= 1.44 × 1011 m



Question 87.

Simplify and express each of the following in exponential form:



Answer:







Question 88.

Simplify and express each of the following in exponential form:


Answer:

[As we know that: am ÷ an = am-n]

Therefore,

[We also know that, am × an = am + n


Question 89.

Simplify and express each of the following in exponential form:



Answer:

(37 ÷ 35)4

⟹ (37-5)4


⟹ (32)4


⟹ 38



Question 90.

Simplify and express each of the following in exponential form:



Answer:







Question 91.

Simplify and express each of the following in exponential form:



Answer:







Question 92.

Simplify and express each of the following in exponential form:



Answer:







Question 93.

Evaluate



Answer:




⟹ 49a2b3



Question 94.

Evaluate



Answer:



⟹ 5(4-3) × 7(4-2) × 2(7-3)


⟹ 51 × 72 × 24


⟹ 5 × 49 × 16


= 3920



Question 95.

Evaluate



Answer:








Question 96.

Evaluate



Answer:





⟹ 34 × 32


= 36


= 729



Question 97.

Evaluate



Answer:








Question 98.

Evaluate



Answer:








Question 99.

Evaluate



Answer:




= 1



Question 100.

Express the given information in Scientific notation (standard form) and then arrange them in ascending order of their size.



Answer:


The ascending order is as follows:


1.554 × 105; 1.9943 × 105; 6.475 × 105; 9.324 × 105; 8.5988 × 106


Gibson, Australia; Thar, India; Great Victoria, Australia, Kalahari, South Africa, Sahara, North Africa



Question 101.

Express the given information in Scientific notation and then arrange them in descending order of their size.



Answer:


The descending order is as follows:


1.9 × 1027; 5.69 × 1026; 1.02 × 1026; 8.69 × 1025; 5.98 × 1024; 4.87 × 1024; 6.42 × 1023; 3.3 × 1023; 1.31 × 1022


Jupiter > Saturn > Neptune > Uranus> Earth > Venus > Mars > Mercury >Pluto



Question 102.

Write the number of seconds in scientific notation.



Answer:



Question 103.

In our own planet Earth, 361,419,000 square kilometre of area is covered with water and 148,647,000 square kilometre of area is covered by land. Find the approximate ratio of area covered with water to area covered by land by converting these numbers into scientific notation.


Answer:

Area covered by water = 361,419,000 square kilometre


Area covered by land = 148,647,000 square kilometre


Ratio = 361,419,000 / 148,647,000


Ratio = 12:5


Area covered by water in standard notation = 3.61419 × 108


Area covered by land in standard notation = 1.48647 × 108



Question 104.

If 2n + 2 – 2n + 1 + 2n = c × 2n, find the value of c.


Answer:




c = 4 – 2 + 1


c = 3



Question 105.

A light year is the distance that light can travel in one year.

1 light year = 9,460,000,000,000 km.

(a) Express one light year in scientific notation.

(b) The average distance between Earth and Sun is 1.496 × 108 km. Is the distance between Earth and the Sun greater than, less than or equal to one light year?



Answer:

(a) For the standard form notation, only one number is kept before the decimal point and rest all numbers are written after decimal point.

The power of 10 denotes the number of terms shifted after the decimal point.


So for 9,460,000,000,000


Here only one number will be kept before decimal point that is 9.


Number of terms to be shifted after decimal point = 12



9,460,000,000,000 = 9.46 × 1012 km


(b) One light year = 9.46 × 1012 km


Distance between Sun and Earth = 1.496 × 108 km


It is clearly seen that one light year is greater than the distance between sun and earth.



Question 106.

Geometry Application : The number of diagonals of an n-sided figure is (n2 –3n).

Use the formula to find the number of diagonals for a 6-sided figure (hexagon).



Answer:

Given:


Number of sides in hexagon, n = 6





So number of diagonals = 9



Question 107.

Life Science : Bacteria can divide in every 20 minutes. So 1 bacterium can multiply to 2 in 20 minutes. 4 in 40 minutes, and so on. How many bacteria will there be in 6 hours? Write your answer using exponents, and then evaluate.



Answer:

1 hour = 60 minutes

So 6 hours = 60 × 6


= 360 minutes


As mentioned in the question bacteria doubles itself in every 20 minutes.


So number of times bacteria doubles itself in 360 min = 360 / 20


= 18


∴ Number of bacteria in 6 hours = 218



Question 108.

Blubber makes up 27 per cent of a blue whale’s body weight. Deepak found the average weight of blue whales and used it to calculate the average weight of their blubber. He wrote the amount as 22 × 32 × 5 × 17 kg. Evaluate this amount.



Answer:

Given:

Weight of blubber = 22 × 32 × 5 × 17 kg


= 4 × 9 × 5 × 17


= 36 × 85


= 3060 kg



Question 109.

Life Science Application : The major components of human blood are red blood cells, white blood cells, platelets and plasma. A typical red blood cell has a diameter of approximately 7 × 10–6 metres. A typical platelet has a diameter of approximately 2.33 × 10–6 metre. Which has a greater diameter, a red blood cell or a platelet?


Answer:

Given:

Diameter of red blood cells = 7 × 10–6 metres


Diameter of platelets = 2.33 × 10–6 metre


It is clearly observed that the diameter of the red blood cell is greater than as compared to the diameter of the platelets.



Question 110.

A googol is the number 1 followed by 100 zeroes.

(a) How is a googol written as a power?

(b) How is a googol times a googol written as a power?


Answer:

(a) Given:

A googol is the number 1 followed by 100 zeroes.


So in standard notation 1 googol = 1 × 10100


(b) Googol times a googol = (1 × 10100) × (1 × 10100)


= 10100 + 100


= 10200



Question 111.

What’s the error?

A student said that is the same as what mistake has the student made?


Answer:








The mistake performed by the student was of multiplying the base with its exponent.