Class 8 Maths NCERT Solutions Chapter 12 – Exponents and Powers

Class 8 Maths NCERT Solutions Chapter 12: Exponents and Powers

Ex – 12.1

Question 1.
Evaluate :
(i) 3−2
(ii) −4−2
(iii) (1\2)−5
Solution.

Question 2.
Simplify and express the result in power notation with positive exponent.

Solution.

Question 3.
Fmd the value of:

Solution.

Question 4.
Evaluate
(i) 8−1×532−4
(ii) (5−1×2−1)×6−1
Solution.

Question 5.
Find the value of m for which 5m+5−3=55
Solution.

Question 6.
Evaluate :

Solution.

Question 7.
Simplify:
(i) 25×t−45−3×10×t−8 (t ≠ 0)
(ii) 3−5×10−5×1255−7×6−5
Solution.

Ex – 12.2

Question 1.
Express the following numbers in standard form:
(i) 0.0000000000085
(ii) 0.00000000000942
(iii) 6020 000 000 000 000
(iv) 0.00000000837
(v) 31860000000
Solution.

Question 2.
Express the following numbers in usual form:

Solution.

Question 3.
Express the number appearing in the following statements in standard form:
(i) 1 micron is equal to [Math Processing Error]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.

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 ?
Solution.
Total thickness of books
= 5 x 20 mm = 100 mm
Total thickness of paper sheets
= 5 x 0.016 mm = 0.080 mm
∴ Total thickness of the stack
= Total thickness of books + Total thickness of paper sheets
= 100 mm + 0.080 mm
= (100 + 0.080) mm
= 100.080 mm
= 1.0008 x [Math Processing Error] mm.