Maths NCERT Class 8 EXPONENTS AND POWERS 104 MCQs
EXPONENTS AND POWERS
1. The value of a° is
(a) 0
(b) 1
(c) 2
(d) a
Answer: (b) 1
Solution:
(any number)°=1
(i.e.) a°=1
2. The exponent of aman is
(a) amn
(b) am+n
(c) am-n
(d) amn
Answer: (b) am+n
Solution:
For any non-zero integer a as bases and exponents as m, n then
aman= am+n
3. The exponent form of -2-5-2-6 is
(a) 1-210
(b) 1-212
(c) 1-211
(d) 1-28
Answer: (c) 1-211
Solution:
-2-5-2-6= -2-5+(-6)
= -2-11=1-211
4. The exponent of 10410-12 is
(a) 1106
(b) 1104
(c) 1108
(d) 1105
Answer: (c) 1108
Solution:
10410-12=104+-12=104-12=10-8=1108
5. The exponential of 343-638 is
(a) 35
(b) 36
(c) 34
(d) 37
Answer: (b) 36
Solution:
343-638=34+-6+8=36
=312-6=36
6. For any non-zero integer a as aman is
(a) am+n
(b) an-m
(c) am-n
(d) amn
Answer: (c) am-n
Solution:
For any non-zero integer a as base and aman=ama-n=am+-n=am-n
7. The value of 4-2 is
(a) 818
(b) 116
(c) 110
(d) 16
Answer: (b) 116
Solution:
4-2=142=116
8. The simplified form of -5-4 is
(a) 625
(b) 1625
(c) 1525
(d) 1425
Answer: (b) 1625
Solution:
-5-4=1-54=1-5-5-5-5=1625
9. The value of 1n is
(a) n
(b) 0
(c) 1
(d) -1n
Answer: (c) 1
Solution:
11=12=13=1
1-1=1-2=1-3=1
In general 1n=1 for any integer ‘n’
10. 12-5 has the simplified form as
(a) 30
(b) 34
(c) 32
(d) 36
Answer: (c) 32
Solution:
12-5=1125=11212121212=1132=32
11. The correct form of amn is
(a) am+n
(b) amn
(c) am-n
(d) amn
Answer: (b) amn
Solution:
For any non-zero integer ‘a’ as base and exponent as m and n then
amn=amn
12. The exponent of ambm is
(a) am+n
(b) abm
(c) abm-n
(d) abmn
Answer: (b) abm
Solution:
For any non-zero integers a and b as bases and exponent as m and n then
ambn=abm
13. The value of -54-56 is
(a) 125
(b) 120
(c) 110
(d) 115
Answer: (a) 125
Solution:
-54-56
=-54-56
=-54-5-6
=-54+-6
=-5-2
=1-5-2=1-5-5=125
14. The result of 1234 in power notation with positive exponent is
(a) 1210
(b) 1212
(c) 128
(d) 1214
Answer: (b) 1212
Solution:
1234=1234=123×4=1212=1212 ∵amn=amn
∵ 13=1
∴123=1323=123
15. The result of -32532 in power natation with positive exponent is
(a) 54
(b) 52
(c) 56
(d) 53
Answer: (b) 52
Solution:
-32532=-3532 ∵ ambm=abm
=-1×52=-1252
=1×52=52
16. The power natation with positive natation exponent of 4-64-84-5 is
(a) 142
(b) 143
(c) 145
(d) 144
Answer: (b) 143
Solution:
4-64-84-5=4-64-84-5
=4-6484-5 ∵ aman=am+n
=4-6+84-5
=424-5
=42+-5
=4-3=143
17. The result of 3-3-6-3 in power notation with positive exponents is
(a) 1183
(b) 1186
(c) 1-183
(d) 1-186
Answer: (c) 1-183
Solution:
3-3-6-3=3×-6-3 ∵ ambm=abm
=-18-3
=1-183
18. The exponent form of ambm is
(a) ab-m
(b) abm
(c) ba2m
(d) ba-2m
Answer: (b) abm
Solution:
ambm=ab-m for any non-zero integers a and b and m as exponents
19. The value of 40+9732 is
(a) 8
(b) 10
(c) 6
(d) 12
Answer: (b) 10
Solution:
40+9732=1+1932
=9+1932=109×9=109+19×9
= 10
20. The simplified form 3-1+9-13-2 is
(a) 12
(b) 15
(c) 13
(d) 14
Answer: (c) 13
Solution:
3-1+9-13-2=3×9-13-2
=3132-13-2
=33-13-2 ∵ ambm=abm
=3-33-2
=3-33-2=3-3 32=3-3+2=3-1=13
21. The value of 13-2+14-2+15-2 is
(a) 40
(b) 50
(c) 70
(d) 45
Answer: (b) 50
Solution:
13-2+14-2+15-2=9+16+25=50
∴13-2=1132=119=9
14-2=1142=1116=16
15-2=1152=1125=25
22. The simplified form of 2-1+3-1+6-10 is
(a) 1
(b) 3
(c) 2
(d) 4
Answer: (a) 1
Solution:
2-1+3-1+6-10=12+13+160 ∵ x-m =1xm
=3+2+160
=660=10=1 ∵ a0=1
23. The value of -35-32 is
(a) 16625726
(b) 16625729
(c) 16624726
(d) 16624723
Answer: (b) 16625729
Solution:
-35-32=-35-3×2 ∵ amn=amn
=35-6
=-3-65-6 ∵ abm=ambm
=56-36
=5×5×5×5×5×5-3-3-3-3-3-3
=15625759
24. The simplest of 8-1522-3 is
(a) 20
(b) 40
(c) 30
(d) 50
Answer: (d) 50
Solution:
8-1522-3=8-1×5×52-4=1824×5×5
=18×2×2×2×2×25=50
= 50
25. The value of 4-13-15-1 is
(a) 160
(b) 140
(c) 150
(d) 130
Answer: (a) 160
Solution:
4-13-15-1=4×3-15-1 ∵ ambm=abm
=12-15-1
=12×5-1
=60-1
=160 ∵ a-m=1am
26. If the 6x6-4=65 then the value of x is
(a) 2
(b) 1
(c) 4
(d) 6
Answer: (b) 1
Solution:
6x6-4=65
6x6-4=65
6x 64=65
6x+4=65
The exponents are equal since the bases are equal
∴ x+4=5 ⇒x=5-4
(i.e.) x=1 ∴ x=1
27. The simplification of 15-116-1-1 is
(a) -1
(b) 1
(c) 2
(d) 3
Answer: (a) -1
Solution:
15-116-1-1=115-115-1 ∵ a-m=1am
=5-6-1
=-1-1
=-1
28. The value of 35-553-3 is
(a) 235
(b) 214
(c) 259
(d) 223
Answer: (c) 259
Solution:
35-553-3=35-5353 ∵ a-m=1am
=35-5+3 53-3=153-3=353
=35-2
=53-2
=5232 ∵ abm=ambm
=5×53×3=259
29. The rational number of 32-3 is
(a) 523
(b) 827
(c) 625
(d) 324
Answer: (b) 827
Solution:
32-3=1323=13323=2333=2×2×23×3×3=827
∵ a-m=1am, ambm=abm
30. If -25-3 is the given form then the rational number is
(a) -1258
(b) 12516
(c) 12315
(d) 12512
Answer: (a) -1258
Solution:
-25-3=1-253=1-2353=53-23=5×5×5-2×-2×-2
=-12516=-1258
=12516=-1258
31. The rational form of -23-1-352 is
(a) 2534
(b) 2712
(c) 2750
(d) 2516
Answer: (c) 2750
Solution:
-23-1-352=1-231-352
=321-352
=3121-3252 ∵ abm=ambm
=32-3-35×5
=2750
32. The power of a rational number with positive exponent of 5-25-4 is
(a) 153
(b) 156
(c) 154
(d) 152
Answer: (b) 156
Solution:
5-25-4=152154 ∵ a-m=1am
=1×15254
= 152+4 ∵ aman=am+n
=156=1656=156 ∵ abm=ambm
33. The positive exponent of -12-2-12-3 is
(a) 25
(b) 23
(c) -25
(d) -32
Answer: (c) -25
Solution:
-12-2-12-3=-12-2+-3
=-12-5
=1-125
=1-1525=25-15=25-1=-25
34. The value of 3-14-12-45-1 is
(a) 209
(b) -209
(c) 103
(d) -103
Answer: (b) -209
Solution:
3-14-12-45-1=131421-45
=134125-4
=4325-4
=42325-4
=49-51
=-209
35. The simplified form of 3-1-4-1-1+2-1-3-1-1 is
(a) 20
(b) 16
(c) 18
(d) 14
Answer: (c) 18
Solution:
3-1-4-1-1+2-1-3-1-1=13-14-1+12-13-1 ∵a-m=1am
=4-312-1+3-26-1
=112-1+16-1
=1112+116
=12+6=18
36. The value of 3-1-4-1-16-1 is
(a) 74
(b) 72
(c) 76
(d) 70
Answer: (b) 72
Solution:
3-1-4-1-16-1=13-14-116
=112-161
=111261 ∵a-m=1an
=12×6=72
37. The simplified value of 3-1+6-123-1 is
(a) 13
(b) 12
(c) 14
(d) 15
Answer: (a) 13
Solution:
3-1+6-123-1=13+161231
=2+1632
=3623=13
38. The value of 4-1+23-1-1 is
(a) 45
(b) 47
(c) 49
(d) 411
Answer: (b) 47
Solution:
4-1+23-1-1=14+123-1
=14+32-1
=1+64-1
=74-1
=174=47
39. Given 3-1+4-12, the rational number of the form pq is
(a) 49142
(b) 49140
(c) 49144
(d) 49146
Answer: (c) 49144
Solution:
3-1+4-12=13+142 ∵a-m=1an
=4+3122
=7122
=72122 ∵ ambm=abm
=49144
40. The rational form 3-1-6-12 is
(a) 135
(b) 136
(c) 132
(d) 134
Answer: (b) 136
Solution:
3-1-6-12=13-162=2-162=162=1262=136 ∵abm= ambm
41. The value of 13-1-23-1-1 is
(a) 23
(b) 25
(c) 27
(d) 211
Answer: (a) 23
Solution:
13-1-23-1-1=113-123-1
=31-32-1
=6-32-1
=32-1=132=23
42. The rational form of -4-3 is
(a) -154
(b) 164
(c) -164
(d) 134
Answer: (c) -164
Solution:
-4-3=1-43=1-4×-4×-4=-164
43. 23-2 has the rational form as
(a) 49
(b) 94
(c) 23
(d) 45
Answer: (b) 94
Solution:
23-2=1232=12232=3222=94 ∵abm= ambm
44. The value of 13-2 is
(a) 8
(b) 10
(c) 9
(d) 7
Answer: (c) 9
Solution:
13-2=32=9
45. The simplified form of 12-5
(a) 32
(b) 34
(c) 30
(d) 36
Answer: (a) 32
Solution:
12-5=1125=11525=2515-321=32
= 32
46. The value of 3-1+4-1 is
(a) 710
(b) 78
(c) 79
(d) 712
Answer: (d) 712
Solution:
3-1+4-1=13+14=4+312=112
47. The simplified form of 20+4-132 is
(a) 434
(b) 454
(c) 452
(d) 435
Answer: (b) 454
Solution:
20+4-132=1+14×9
=54×9
=454
48. The value of 13-1+14-1+15-1 is
(a) 10
(b) 14
(c) 12
(d) 8
Answer: (c) 12
Solution:
13-1+14-1+15-1=113+114+115
=31+41+51=121=12
49. The simplified form of 3-16-13-2 is
(a) 13
(b) 14
(c) 12
(d) 15
Answer: (c) 12
Solution:
3-16-13-2=1316132
=11819
=11891=12
50. The simplified form of 5-14-12 is
(a) 1400
(b) 1169
(c) 1196
(d) 1144
Answer: (a) 1400
Solution:
5-14-12=15142=1202=12202=1400 ∵abm= ambm
51. The value of 6-17-13 is
(a) 342213
(b) 343216
(c) 341212
(d) 340213
Answer: (b) 343216
Solution:
6-17-13=16173=16×73=763=7363=343216
52. The simplest form of 4-1+5-1-1 is
(a) 209
(b) 109
(c) 119
(d) 89
Answer: (a) 209
Solution:
4-1+5-1-1=14+15-1 ∵ a-m=1am
=5+420-1
=920-1=1920=209=209
53. The value of 4-15-1-16-1 is
(a) 53
(b) 107
(c) 103
(d) 52
Answer: (c) 103
Solution:
4-15-1-16-1=1415-116
=120-116
=112016
=20×16
=103
54. The value after simplification of 42+32133 is
(a) 2527
(b) 2325
(c) 2521
(d) 2119
Answer: (a) 2527
Solution:
42+32133=16+91333 ∵abm= ambm
=25×127=2527
55. The value of 42-3234-3 is
(a) 44627
(b) 44827
(c) 44027
(d) 44227
Answer: (b) 44827
Solution:
42-3234-3=16-91343
=7×13343 ∵abm= ambm
=7×4333
=7×6427=44827
56. The simplest form of 14-3-13-315-3 is
(a) 35124
(b) 36125
(c) 37125
(d) 35122
Answer: (c) 37125
Solution:
14-3-13-315-3=1143-11331153
=11343-1133311353
=43-3353
=64-27125
=37125
57. The value of 52+42-32432 is
(a) 10
(b) 12
(c) 16
(d) 18
Answer: (d) 18
Solution:
52+42-32432 =25+16-9169
=32÷169
=32916
=18
58. The number of be multiplied with 5-1 so that the product is equal to -7-1 is
(a) 57
(b) -57
(c) 37
(d) 47
Answer: (b) -57
Solution:
Let ‘x’ be the number multiplied with 5-1 to get -7-1
(i.e.) x=5-1=-7-1
x=-7-15-1=1-715=-1751=-57
=-57
59. -47-1 is the product of two numbers. If one number is 12-1 then the other number is
(a) 78
(b) 57
(c) -78
(d) 35
Answer: (c) -78
Solution:
Let ‘x’ be then number to be multiplied with 12-1
(i.e.) x×12-1=-47-1
(i.e.) x=-47-112-1=12-47=12-74=-78
60. The number to be divided by -36-1 so that the quotient is equal to -6-1
(a) 16
(b) 15
(c) 13
(d) 12
Answer: (a) 16
Solution:
Let ‘x’ be the number divides -36-1 to get -6-1
(i.e.) -36-1÷x=-6-1
-36-11x=-6-1
(i.e.) 1-36x=-6-1
(i.e.) 1-36x=1-6
(i.e.) x=636=16
61. The square of -45 is
(a) 165
(b) 1625
(c) -1625
(d) 425
Answer: (b) 1625
Solution:
-452=-4252=-4-45×5=1625
62. The cube of -13 is
(a) 125
(b) -125
(c) 127
(d) -127
Answer: (d) -127
Solution:
-133=-1333=-1-1-13×3×3=-127
63. The following number which is not same as -454
(a) -4544
(b) -4544
(c) 44-54
(d) -45-45-45-45
Answer: (b) -4544
Solution:
-454=-4454=44-54=-45-45-45-45
-454-4454 (∵ Even power does not end up with negative value)
64. The following number which is not reciprocal of 563
(a) 65-3
(b) 653
(c) 6353
(d) 56-3
Answer: (a) 65-3
Solution:
Reciprocal of 563 is 653=6353
(i.e.) 653=165-3=16-35-3=5-36-3=56-3
563=156-3=15-36-3=6-35-3=65-3
Clearly 65-3 is not reciprocal of 563
65. The following number which is not equal to -2764 is
(a) -34-3
(b) -343
(c) 34-3
(d) -34-34-34
Answer: (c) 34-3
Solution:
(a) -34-3=-3343=3×3×34×4×4=-2764
(b) -343=-34-34-34=-2764
(c) 34-3=3-34-3=4333=433=6427
(d) -34-34-34=-2764 ∴ 34-3 is not equal is -2764
66. The exponential form of 43-143-143-143-1 is
(a) 81256
(b) 80253
(c) 81251
(d) 81254
Answer: (a) 81256
Solution:
43-143-143-143-1=143143143143 ∵ a-m=1am
=34343434
=81256
67. 35-235-235-2 has the exponents form as
(a) 15628725
(b) 15627724
(c) 15626723
(d) 15625729
Answer: (d) 15625729
Solution:
35-235-235-2=135213521352
=132521325213252
=523252325232
=259259259
=15625729
68. The rational number of the form pq of the number 57-173-1 is
(a) 25
(b) 15
(c) 35
(d) 45
Answer: (c) 35
Solution:
57-173-1=157173
=7537
=35
69. The rational number of -5-1-43-1 is
(a) 310
(b) 720
(c) 320
(d) 910
Answer: (c) 320
Solution:
-5-1-45-1=1-51-43
=-15-34
=320
70. The value of 4-15-13 is
(a) 12564
(b) 12362
(c) 12063
(d) 12461
Answer: (a) 12564
Solution:
4-15-13=14153
=14×53
=543=5343 ∵abm= ambm
=12564
71. The negative exponents of the rational number 534-2 is
(a) 53-2
(b) 53-4
(c) 53-6
(d) 53-8
Answer: (d) 53-8
Solution:
534-2=53-8
72. The negative exponents of the rational number 574 is
(a) 75-2
(b) 57-4
(c) 75-4
(d) 57-2
Answer: (c) 75-4
Solution:
574=157-4=15-47-4=7-45-4=75-4
73. The negative exponents of 57 is
(a) 5-7
(b) 15-7
(c) 17-5
(d) 7-5
Answer: (b) 15-7
Solution:
57=15-7=1-75-7=15-7 ∵ a-m=1am
74. The rational number 153 has the negative exponents as
(a) 5-3
(b) 3-5
(c) 15-3
(d) 13-5
Answer: (a) 5-3
Solution:
153=1353=5-3 ∵abm= ambm
75. The positive exponents of the rational number 54-4-3 is
(a) 547
(b) 5412
(c) 543
(d) 4512
Answer: (b) 5412
Solution:
54-4-3=54-4×-3=5412
76. The positive exponents of the rational number 45-3 is
(a) 453
(b) 153
(c) 543
(d) 143
Answer: (c) 543
Solution:
45-3=1453=14353=5343=543
77. The positive exponent of 525-4 is
(a) 153
(b) 152
(c) 154
(d) 151
Answer: (b) 152
Solution:
525-4=5254=5×55×5×5×5=152=152
78. The simplified form of -122-2-1 is
(a) 14
(b) 116
(c) 112
(d) 110
Answer: (b) 116
Solution:
-122-2-1=-122-2=-124=-1424=12×2×2×2
=116
79. The simplest form by 14-7-8-1-1 is
(a) 2
(b) -3
(c) -2
(d) 3
Answer: (c) -2
Solution:
14-7-8-1-1=1141-8-1
=4-8-1
=-12-1
=1-12=-2
80. The simplified form of 232313-43-16-1 is
(a) 3281
(b) 3180
(c) 3285
(d) 3185
Answer: (a) 3281
Solution:
232313-43-16-1=23611341316
=2636114341316
=263634141316
=2634-61316
=26321316
=64613×32
=323133=323×3×3×3
=3281
81. If 12-212-4=12-2x then the value of x is
(a) 3
(b) 2
(c) 4
(d) 5
Answer: (a) 3
Solution:
12-212-4=12-2x
12-2-4=126=12-2x
Since bases are equal
∴ Exponents are equal
(i.e.) -6=-2x
x=-6-2=3
82. If 13213-4=132m-1 then the value of ‘m’ is
(a) 12
(b) 13
(c) -12
(d) -13
Answer: (c) -12
Solution:
13213-4=132m-1
132-4=132m-1-2=132m-1
Since bases are equal therefore it exponents are equal
-2=2m-1
(i.e.) -2+1=2m
(i.e.) -1=2m
(i.e.) m=-12
83. If x=32223-4 then the value of x-1 is
(a) 326
(b) 236
(c) 325
(d) 235
Answer: (b) 236
Solution:
x=32223-4
=32221234
=9412434
=943424
=3×32×23×3×3×32×2×2×2=3626=326
x=326
∴ x-1=32-6=236
84. If x=45-2142 then the value of x-2 is
(a) 5-2
(b) 5-4
(c) 4-3
(d) 4-2
Answer: (b) 5-4
Solution:
x=45-2142
=45-2412
=4121452
=4214252
x=52
∴x-2= 52-2=5-4 ⇒ x-2=5-4
85. The value of ‘x’ for which 32x3-4=36 is
(a) 2
(b) 4
(c) 1
(d) 5
Answer: (c) 1
Solution:
32x3-4=36 ⇒ 32x3-4=36 ⇒32x34=36
32x34=36
32x+4=36 ∵ aman=am+n
Since bases are equal therefore its exponents is equal
2x+4=6
2x=2
x=1
86. The suitable number of the given exponent 1×103+4×101+5×100+6×10-1+2×10-2 is
(a) 1025.63
(b) 1045.62
(c) 1035.64
(d) 1065.67
Answer: (b) 1045.62
Solution:
1×103+4×101+5×100+6×10-1+2=1×1000+0×100+4×10+5×1+610+2100
=1000+0+40+5+0.6+0.002
=1045.62
87. The number which corresponds to given exponents
1×103+3×102+2×101+7×100+2×10-1+6×10-2+8×10-3 is
(a) 1347.286
(b) 1327.628
(c) 1237.628
(d) 1327.268
Answer: (d) 1327.268
Solution:
1×103+3×102+2×101+7×100+2×10-1+6×10-2+8×10-3
=1×1000+3×100+2×10+7×1+210+6100+81000
=1000+300+20+7+.2+.06+.008
= 1327.268
88. The standard form of the given number 0.000000465 is
(a) 4.65×10-5
(b) 4.65×10-6
(c) 4.65×10-7
(d) 4.65×10-4
Answer: (c) 4.65×10-7
Solution:
0.000000465=4651,000,000,000
=4.65109102
=4.65107
=4.65×10-7
89. The standard form of 62100000 is
(a) 6.21×107
(b) 6.21×105
(c) 6.21×104
(d) 6.21×103
Answer: (a) 6.21×107
Solution:
62100000=621×100000
=6.21×100×100000
=6.21×102105
=6.21×107
90. The standard form of 0.0000051 is
(a) 5.1×10-5
(b) 5.1×10-6
(c) 5.1×10-4
(d) 5.1×10-3
Answer: (b) 5.1×10-6
Solution:
0.0000051=5110000000
=5.1×1010000000
=5.11000000=5.1106=5.1×10-6
91. The standard form of the number 26350000 is
(a) 2.635×105
(b) 2.635×103
(c) 2.635×104
(d) 2.635×107
Answer: (d) 2.635×107
Solution:
26350000=2635×10000
=2.635×1000×10000
=-2.635×103104
=2.635×107
92. The usual form of the given number 5.03×10-6 is
(a) .0000503
(b) .000503
(c) .00000503
(d) .000000503
Answer: (c) .00000503
Solution:
5.03×10-6=503×10-210-6
=503×10-8
=503100,000,000
= .00000503
93. The usual form of the number 4.7×1012 is
(a) 4700000000
(b) 4700000000000
(c) 47000000000
(d) 47000000
Answer: (b) 4700000000000
Solution:
4.7×1012=4710×1,000,000,000,000
=47×100,000,000,000
= 4700000000000
94. The usual form of 5×10-8 is
(a) .0000005
(b) .000005
(c) .000005
(d) .00000005
Answer: (d) .00000005
Solution:
5×10-8=51,00,000,000=.00000005
95. The number 2.0002109 has the usual form as
(a) 2002000
(b) 200200
(c) 20020000
(d) 200200000
Answer: (d) 200200000
Solution:
2.0002109=2000210000×1,000,000,000
=2002×100000
=200,200,000
96. The usual form of 5.42639×106 is
(a) 5426930
(b) 5426390
(c) 5426039
(d) 5426309
Answer: (b) 5426390
Solution:
5.42639×106=542639100,000×1,000,000
=542639×10
= 5426390
97. The standard form of 0.0000000000058 is
(a) 5.8×10-8
(b) 5.8×10-11
(c) 5.8×10-12
(d) 5.8×10-7
Answer: (c) 5.8×10-12
Solution:
0.0000000000058=5810000000000000
=581013
=5.8×101013
=5.81012=5.8×10-12
98. The standard form of 7030000000000000 is
(a) 7.03×1013
(b) 7.03×1012
(c) 7.03×1015
(d) 7.03×1014
Answer: (c) 7.03×1015
Solution:
7030000000000000 =703×10,000,000,000,0000
=703×1013
=7.03×1021013
=7.03×1015
99. The standard form of 1 micron is equal to 11,000,000 m is
(a) 1×10-5
(b) 1×10-7
(c) 1×10-6
(d) 1×10-8
Answer: (c) 1×10-6
Solution:
Given 11000000=1106=1×10-6 m
(i.e.) 1 micron =1×10-6 m
100. The standard form of size of a bacteria. 0000005m is
(a) 5×10-6
(b) 5×10-5
(c) 5×10-7
(d) 5×10-4
Answer: (c) 5×10-7
Solution:
Given 0.0000005=510,000,000=5107=5×10-7
101. In a stack if there are 5 books each of thickness 10mm and 4 paper sheets each of thickness 0.015mm then the total thickness of the stack is
(a) 5.06×101mm
(b) 5.06×102mm
(c) 5.006×101mm
(d) 5.006×102mm
Answer: (c) 5.006×101mm
Solution:
Thickness of one book = 10mm
∴ Thickness of 5 books =5×10mm=50mm
Thickness of 1 paper sheet = 0.015mm
∴ Thickness of 4 paper sheet =4×0.015mm
= 0.06mm
Total thickness = 50mm + 0.06mm
= 50.06mm
= 5.006×101mm
102. The standard form of size of a plant cell 0.00001275m is
(a) 1.275×10-3
(b) 1.275×10-2
(c) 1.275×10-4
(d) 1.275×10-5
Answer: (d) 1.275×10-5
Solution:
Given 0.00001275=1275100000000
=1275108=1.275×103108
=1.275105
=1.275×10-5
103. A number if it is expressed as the product of a number between 1 and 10 and integral power of 10 then it is
(a) usual form
(b) standard form
(c) normal form
(d) general form
Answer: (b) standard form
Solution:
A number is said to be in the standard form if it is expressed as the product of a number between 1 and 10 and integral power of 10.
104. A number is said to be in the standard form when it is written as k×10n where
(a) 1<k<10
(b) 1<k≤10
(c) 1≤k<10
(d) 1≤k≤10
Answer: (c) 1≤k<10
Solution:
A number is said to be in the standard form when it is written as k×10n where 1≤k<10
105. The standard form of thickness of a thick paper 0.07mm is
(a) 7×10-2mm
(b) 7×10-3mm
(c) 7×10-4mm
(d) 7×10-6mm
Answer: (a) 7×10-2mm
Solution:
Given
0.07=7100=7102=7×10-2
∴ Thickness of a thick paper is 7×10-2mm
106. A number is said to be in the standard form when it in written as k×10n where 1≤k<10 and ‘n’ is
(a) whole number
(b) an integer
(c) natural number
(d) positive integer
Answer: (b) an integer
Solution:
A number is said to be in the standard form when it is written as k10n where 1≤k<10 and ‘n’ is an integer.
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