# NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2

**NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Exercise 12.2**

Ex 12.2 Class 8 Maths Question 1.

Express the following numbers in standard form:

(i) 0.0000000000085

(ii) 0.00000000000942

(iii) 6020000000000000

(iv) 0.00000000837

(v) 31860000000

Solution:

(v) 31860000000

= 3.186 × 10000000000

= 3.186 × 10^{10}

Hence, the required standard from = 3.186 × 10^{10}

Ex 12.2 Class 8 Maths 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:

Ex 12.2 Class 8 Maths 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:

Ex 12.2 Class 8 Maths 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:

Thickness of books = 5 × 20 = 100 mm

Thickness of 5 paper sheets = 5 × 0.016 mm = 0.080 mm.

Total thickness of the stack = 100 mm + 0.080 mm = 100.080 mm = 1.0008 × 10^{2} mm