8th Standard CBSE Syllabus & Materials
8th Standard CBSE
CBSE 8th Social Science Theme D - Factors of Production - New Model Questions Papers Study Material - QB365 Set A
NEW8th Standard CBSE
CBSE 8th Social Science Theme C - Universal Franchise and India's Electoral System - New Model Questions Papers Study Material - QB365 Set A
NEW8th Standard CBSE
CBSE 8th Social Science Theme B - The Rise of the Marathas - New Model Questions Papers Study Material - QB365 Set A
NEW8th Standard CBSE
CBSE 8th Social Science Theme B - Reshaping India's Political Map - New Model Questions Papers Study Material - QB365 Set A
NEW8th Standard CBSE
CBSE 8th Social Science Theme A - Natural Resources and Their Use - New Model Questions Papers Study Material - QB365 Set A
NEW8th Standard CBSE
CBSE 8th Science Keeping Time with Skies - New Model Questions Papers Study Material - QB365 Set A

Published on: 20/09/2019
Exponents and Powers
Download CBSE Class 8th Standard CBSE Mathematics question papers, sample papers, important questions, and previous year solved papers in PDF format. Get free study materials, NCERT solutions, and exam preparation resources for Class 8th Standard CBSE Mathematics
Questions + Answers key
Take MCQ Mathematics Test

1.
If the thickness of a paper sheet is 0.0016 cm. Find the thickness of 100 sheets. Express your answer in the standard form.
2.
Simplify: (-5)-5 \(\times\) (-5)4
3.
Express the following numbers in usual form: 3.52 \(\times\) 105
4.
Express the following numbers in standard form: 4050000
5.
What is the value of x in 5x \(\div \) 5-3 = 55?
6.
Find the value of x: 3, if x = (100)1- 4 ÷ (100)0
7.
Find the value of[2-1 x 3-1]-1.
8.
Express the number appearing in the following statements in standard form.
Size of a plant cell is 0.00001275 m.
9.
Express the number appearing in the following statements in standard form.
Size of a bacteria is 0.0000005 m.
10.
If \(16^{\frac{3}{2}}+16^{\frac{-3}{2}}\)=m, then find the value of m.
11.
If 289 = \(17^{\frac{x}{5}}\),then find the value of x.
12.
Evaluate. \({ \left( \frac { 5 }{ 8 } \right) }^{ -7 }\times { \left( \frac { 8 }{ 5 } \right) }^{ -4 }\)
13.
Evaluate {\((\frac{1}{3})^{-1}-(\frac{1}{4})^{-1}\)}-1
14.
Find the multiplicative inverse of the following:
10-5
15.
Find the multiplicative inverse of the following:
2-4
1.
1.6 \(\times\) 10-1
2.
\(\frac { 1 }{ -5 } \)
3.
3.52 x 105 = 3.52 x 100000 = 352000
4.
4.05 \(\times\) 106
5.
x = 2
6.
∵ x=(100)1-4 ÷ (100)0=(100)-3 [∵ (100)0=1]
∴ \(x^{-3}=\frac{1}{x^{3}}=\frac { 1 }{ \left\{ { \left( 100 \right) }^{ -3 } \right\} ^{ 3 } } =\frac{1}{100^{-9}}\) [∵ (am)n=amn]
= 1009
7.
∵ \(2^{-1}\times 3^{-1}=\frac{1}{2}\times \frac{1}{3}=\frac{1}{6}\)
∴ \([2^{-1}\times 3^{-1}]^{-1}=[\frac{1}{6}]^{-1}=6\)
8.
Here, 0.00001275 = \(\frac{1275}{100000000}\)
= \(\frac{1275}{10^{8}}=\frac{1.275 \times 1000}{10^{8}}=1.275\times 10^{3}\times 10^{-8}\) \([\because \frac{1}{a^{m}}=a^{-m}]\)
= 1.275 x 103-8 = 1.275 x 10-5m [∵ amxan = am+n]
Hence, size of a plant cell is 1.275 x 10-5 m.
9.
Here, 0.0000005 = \(\frac{5}{10000000}=\frac{5}{10^{7}}=5\times 10^{-7}m\) \([\because \frac{1}{a^{m}}=a^{-m}]\)
Hence, size of a bacteria is 5 x 10-7 m.
10.
\(\frac{4097}{64}\)
11.
10
12.
\({ \left( \frac { 5 }{ 8 } \right) }^{ -7 }\times { \left( \frac { 8 }{ 5 } \right) }^{ -4 }\) \(\because \quad { a }^{ -m }=\frac { 1 }{ { a }^{ m } } \)
\(\because \quad { \left( \frac { 8 }{ 5 } \right) }^{ -4 }={ \left( \frac { 5 }{ 8 } \right) }^{ 4 }\)
Now, \({ \left( \frac { 5 }{ 8 } \right) }^{ -7 }\times { \left( \frac { 8 }{ 5 } \right) }^{ -4 }={ \left( \frac { 5 }{ 8 } \right) }^{ -7 }\times { \left( \frac { 5 }{ 8 } \right) }^{ 4 }\)
\(={ \left( \frac { 5 }{ 8 } \right) }^{ -7+4 }={ \left( \frac { 5 }{ 8 } \right) }^{ -3 }\) [\(\because\) am \(\times\) an = am+n]
\(={ \left( \frac { 8 }{ 5 } \right) }^{ 3 }=\frac { 8\times 8\times 8 }{ 5\times 5\times 5 } =\frac { 512 }{ 125 } \)
13.
We have , {\((\frac{1}{3})^{-1}-(\frac{1}{4})^{-1}\)}-1
\(\left\{ \frac { { \left( 1 \right) }^{ -1 } }{ { \left( 3 \right) }^{ -1 } } -\frac { { \left( 1 \right) }^{ -1 } }{ { \left( 4 \right) }^{ -1 } } \right\} ^{ -1 }\quad \quad \quad \left[ \because \quad \left( \frac { a }{ b } \right) ^{ m }=\frac { { a }^{ m } }{ { b }^{ m } } \quad \right] \)
\(=\left\{ \frac { 3 }{ 1 } -\frac { 4 }{ 1 } \right\} ^{ -1 }\quad \quad \quad \left[ \because \quad { a }^{ -m }=\frac { 1 }{ { a }^{ m } } \right] \)
= (3-4)-1 = (-1)-1=\(\frac{1}{(-1)^{1}}\) \( \left[ \because \quad { a }^{ -m }=\frac { 1 }{ { a }^{ m } } \right] \)
=\(\frac{1}{-1}=-1\)
14.
We have,10-5=\(\frac{1}{10^{5}}\)
Reciprocal of \(\frac{1}{10^{5}}\)=105
∴ Multiplicative inverse of 10-5 is 105. [\(10^{-5}\times 10^{5}=10^{0}=1\)]
15.
We have ,2-4=\(\frac{1}{2^{4}}\)
Reciprocal of=\(\frac{1}{2^{4}}\)=2-4 [∵ reciprocal of \(\frac{1}{a}\)is a]
∴ Multiplicative inverse of 2-4 is 24. [∵ \(2^{-4}\times2^{4}=2^{0}=1\)]
8th Standard CBSE Syllabus & Materials
8th Standard CBSE
CBSE 8th Science Particulate Nature of Matter - New Model Questions Papers Study Material - QB365 Set A
NEW8th Standard CBSE
CBSE 8th Science Pressure, Winds, Stroms and Cyclones - New Model Questions Papers Study Material - QB365 Set A
NEW8th Standard CBSE
CBSE 8th Mathematics Quadrilaterals - New Model Questions Papers Study Material - QB365 Set A
NEW8th Standard CBSE
CBSE 8th Mathematics A story of Numbers - New Model Questions Papers Study Material - QB365 Set A
CBSE 8th Standard CBSE Subjects
CBSE Standards