Ncert Solutions for Exponents Class 8 maths Chapter 12 CBSE Part 2

Question 1
Express the following numbers in standard form.

1. 0.0000000000085
2. 0.00000000000942
3. 6020000000000000
4. 0.00000000837
5. 31860000000

Answer

1. 0.0000000000085 =8.5 ×10^-12
   
2. 0.00000000000942 =9.42×10^-12
   
3. 6020000000000000 =6.02×10¹⁵
   
4. 0.00000000837 =8.37 ×10^-9
   
5. 31860000000 =3.186×10¹⁰
   

Question 2
Express the following numbers in usual form.

1. 3.02 x 10^-6
2. 4.5 x 10⁴
3. 3 x 10^-8
4. 1.0001 x 10⁹
5. 5.8 x 10¹²
6. 3.61492 x 10⁶

Answer

1. 3.02 x 10^-6 = .00000302
   
2. 4.5 x 10⁴ =45000
   
3. 3 x 10^-8 =.00000003
   
4. 1.0001 x 10⁹ =1000100000
   
5. 5.8 x 10¹² =5800000000000
   

       6. 3.61492 x 10⁶
           =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. 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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Class 8 Maths Class 8 Science