You can Download KSEEB Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 Questions and Answers helps you to revise the complete syllabus.
KSEEB Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2
Question 1.
Express the followoing numbers in standard form.
(i) 0.0000000000085
(ii) 0.00000000000942
(iii) 6020000000000000
(iv) 0.00000000837
(v) 31860000000
Solution:
(i) 0.000,000,000,0085 = 8.5 × 10-12
(ii) 0.00000000000942 = 9.42 × 10-12
(iii) 6020000000000000 = 6.02 × 1015
(iv) 0.00000000837 = 8.37 × 10-9
(v) 31860000000 = 3.186 × 1010
Question 2.
Express the following numbers in usual form.
(i) 3.02 × 10-6
(ii) 4.5 × 104
(iii) 3 × 10-8
(iv) 1.0001 × 109
(v) 5.8 × 1012
(vi) 3.61492 × 106
Solution:
(i) 3.02 × 10-6 = 0.00000302
(ii) 4.5 × 104 = 45000
(iii) 3 × 10-8 = 0.00000003
(iv) 1.0001 × 109 = 1000100000
(v) 5.8 × 1012 = 5800000000000
(vi) 3.61492 × 106 = 3614920
Question 3.
Express the number appearing in the following statements in standard form.
(i) 1 micron is equal to \(\frac{1}{1000000}\) m
(ii) Charge of an electron is 0.000,000,000,000,000,000,16 coulomb.
(iii) Size of a 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.
Solution:
(i) 1 micron = \(\frac{1}{1000000}\) m = 1 × 10-6
(ii) 0.000,000,000,000,000,000,16 coulomb = 1.6 × 10-19 coulomb.
(iii) Size of bacteria is 0.0000005 m = 5 × 10-7 m.
(iv) Size of plant cell is 0.00001275 m = 1.275 × 10-5 m.
(v) Thickness of a thick paper 0.07 mm = 7 × 10-2 mm.
Question 4.
In a stack there are 5 books each of thickness 20mm and 5 paper sheets each of thickness 0.016 mm. What is the total thickness of the stack.
Solution:
Thickness of one book = 20 mm.
Thickness of 5 books = 20 × 5 = 100 mm.
Thickness of 1 sheet of paper = 0.016 mm.
Thickness of 5 sheets of paper = 5 × 0.016 = 0.08 mm.
Total thickness = 100 + 0.08
= 100.08 mm.
= 1.0008 × 102 mm.