Question

7.The mass of a grain of sand is approximately 2.8×10^−11 grams

Answer 1

The Answer is A. Milligram.

Answer 2

Answer :- A) Milligram is the right answer.

Explanation:-

The mass of a grain of sand is approximately $2..8\times10^{-11}\text{ grams}$

We know that 1 gram=1,000 milligrams

Therefore,The mass of a grain of sand is approximately  $=2.8\times10^{-11}\times1000\text{ milligram}\\=2.8\times10^{-11}\times10^3\text {milligram}\\=2.8\times10^{-11+3}\text{ milligram}....\text{[by using law of exponents]}\\=2.8\times10^{-8}\text{ milligram}$

Thus, the  mass of a grain of sand is approximately $2.8\times10^{-8}\text{ milligram}.$