CBSE NCERT Solutions for Class 8 Chapter 12

Our NCERT Solutions act as a practical guide for students who want to effectively prepare for their final examination and score more. NCERT Solutions involve detailed solutions of all NCERT textbook questions.

CBSE NCERT Solutions for Class 8 Maths Chapter 12:

Question-1:

Express the following numbers in standard form .

(i) 0.0000000000085
(ii) 0.00000000000942
(iii) 6020000000000000
(iv) 0.00000000837
(v) 31860000000

Solution:

(i) 0.0000000000085 = 0.0000000000085 * 10^12 / 10^12 = 8.5 ×10-12
(ii) 0.00000000000942 = 0.00000000000942 * 10^12 / 10^12 =9.42×10-12
(iii) 6020000000000000 = 6020000000000000 * 10^15/ 10^15 = 6.02×1015
(iv) 0.00000000837 = = 0.00000000837 * 10^9 / 10^9 = 8.37 ×10-9
(v) 31860000000 = 31860000000 * 10^10/ 10^10 = 3.186×1010

Question-2:

Express the following numbers in usual form.
(i) 3.02 x 10-6
(ii) 4.5 x 104
(iii) 3 x 10-8
(iv)1.0001 x 109
(v) 5.8 x 1012
(vi)3.61492 x 106

Solution:

(i)3.02 x 10-6 = 3.02/ 10^6 = 0 .00000302
(ii)4.5 x 104 =4.5 * 10000 = 45000
(iii)3 x 10-8 = 3/10^8 = 0.00000003
(iv)1.0001 x 109 =1000100000
(v)5.8 x 1012 = 5.8 * 1000000000000 = 5800000000000
(vi) 6. 3.61492 x 106 = 3.61492 1000000 = 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

Solution:

(i) 1 micron = 1/1000000
= 1/10^6
=1×10-6
(ii) Charge of an electron is
0.00000000000000000016 coulombs.
= 0.00000000000000000016 * 10^19 / 10^19
= coulomb
(iii) Size of bacteria = 0.0000005
= 5/10000000 = 5/10^7 = 5 * 10^-7 m
(iv) Size of a plant cell is 0.00001275 m
= 0.00001275 * 10^5/ 10^5 = m
(v) Thickness of a thick paper = 0.07 mm
= 7/100 mm = 7/10^2 = 7* 10^-2 mm