(a).Add `3.8 xx 10^(-6) to 4.2 xx 10^(-5)` with due regard to significant figures.
(b). Subtract `3.2 xx 10^(-6) from 4.7 xx 10^(-4)` with regard to significant figures.
( c ). Subtract `1.5 xx 10^(3) from 4.8 xx 10^(4)` with due regard to significant figures.

Options

A. `4.58 xx 10^(-5) `
B. `4.6 xx 10^(-5)`
C. `4.5 xx 10^(-5)`
D. None of these

Answer

B

Explanation

We will use the general rule of addition by making the powers same.
i.e., we will add `3.8 xx 10^(-6)`
and `42 xx 10^(-6)` we get
` = 45.8 xx 10^(-6) = 4.58 xx 10^(-5)`
As least number of significant figures in given values are 2, so we round off the result to `4.6 xx 10^(-5)`