In this page we have NCERT book Solutions for Class 8th Maths:Exponents and Power Chapter 12 for
EXERCISE 12.2. Hope you like them and do not forget to like , social share
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Question 1
Express the following numbers in standard form.
- 0.0000000000085
- 0.00000000000942
- 6020000000000000
- 0.00000000837
- 31860000000
Answer
- 0.0000000000085
=8.5 ×10^{-12}
- 0.00000000000942
=9.42×10^{-12}
- 6020000000000000
=6.02×10^{15}
- 0.00000000837
=8.37 ×10^{-9}
- 31860000000
=3.186×10^{10}
Question 2
Express the following numbers in usual form.
- 3.02 x 10^{-6}
- 4.5 x 10^{4}
- 3 x 10^{-8}
- 1.0001 x 10^{9}
- 5.8 x 10^{12}
- 3.61492 x 10^{6}
Answer
- 3.02 x 10^{-6}
= .00000302
- 4.5 x 10^{4}
=45000
- 3 x 10^{-8}
=.00000003
- 1.0001 x 10^{9}
=1000100000
- 5.8 x 10^{12}
=5800000000000
6. 3.61492 x 10
^{6}
=3614920
Question 3
Express the number appearing in the following statements in standard form.
(i) 1 micron is equal to 1/1000000 m.
(ii) Charge of an electron is 0.000, 000, 000, 000, 000, 000, 16 coulomb.
(iii) Size of bacteria is 0.0000005 m
(iv) Size of a plant cell is 0.00001275 m
(v) Thickness of a thick paper is 0.07 mm
Answer
- 1/1000000
=1×10
^{-6}
^{ }2. 0.000, 000, 000, 000, 000, 000, 16
=1.6 ×10
^{-19}
3. 0.0000005
=5 ×10
^{-7}
4. 0.00001275
=1.275 ×10
^{-5}
5. 0.07
=7×10
^{-2}
Question 4
In a stack there are 5 books each of thickness 20 mm and 5 paper sheets each of thickness 0.016 mm. What is the total thickness of the stack?
Answer
Total thickness
=5×20 + 5X.016
=100 + 5× 1.6 ×10
^{-2}
=100 + .08
=100.08 mm
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