Question

The order of magnitude of diameter of earth is (diameter of earth is \[{\mathbf{1}}.{\mathbf{28}} \times {\mathbf{1}}{{\mathbf{0}}^7}{\mathbf{m}}\])
(A ) 5
(B) 6
(C) 7
(D) 8

Answer 1

Hint-Order of magnitude is used to make approximate comparison.The term is generally used in conjunction with power-of-10.ie; we always take the power of the 10 when numerical value is expressed in the form of "decimal after one digit and 10 raise to the powers.

Complete step by step solution
We have given diameter of earth is \[1.28 \times {10^7}m\;\]
Order of magnitude
 It is the quantity of powers of 10 that there are in a number, or the number of powers of 0.1 in a
negative number. Order of magnitude is usually written as 10 to the nth power. The n represents the
order of magnitude.
 If you raise a number by one order of magnitude, you are basically multiplying
that number by 10. If you decrease a number by one order of magnitude, you are basically
multiplying that number by 0.1.

So now in our question the diameter of earth is \[1.28 \times {10^7}m\;\].here Order of the diameter of the earth is 7 because we always take the power of the 10 when numerical value is expressed in the form of "decimal after one digit and 10 raise to the powers

So option C is correct

Note :- For other example in the number the number \[1,000,00\], we will shift the decimal to the left,
stopping just before the first digit of the number. The number of moves you make to the left is the
order of magnitude. Since we moved it five times, there are five orders of magnitude of \[1,000,00\]
meaning that you can multiply 10 five times and get \[1,000,00\].