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 × 10^{15}

(iv) 0.00000000837 = 8.37 × 10^{-9}

(v) 31860000000 = 3.186 × 10^{10}

Question 2.

Express the following numbers in usual form.

(i) 3.02 × 10^{-6}

(ii) 4.5 × 10^{4}

(iii) 3 × 10^{-8}

(iv) 1.0001 × 10^{9}

(v) 5.8 × 10^{12}

(vi) 3.61492 × 10^{6}

Solution:

(i) 3.02 × 10^{-6} = 0.00000302

(ii) 4.5 × 10^{4} = 45000

(iii) 3 × 10^{-8} = 0.00000003

(iv) 1.0001 × 10^{9} = 1000100000

(v) 5.8 × 10^{12} = 5800000000000

(vi) 3.61492 × 10^{6} = 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 × 10^{2} mm.