Answer
6.11 x $10^{5}$ µg is the mass of 611mg acid cetic expressed in micrograms.
Work Step by Step
We are required to convert mg (milligram) to µg ( microgram). Both mg and µg are units of mass in international system of unit SI.
From the SI we know that 1 mg = $10^{-3}$ g
From the SI we know 1 µg= $10^{-6}$ g, or 1 g = $10^{6}$µg
So we can convert 611 mg to g:
611mg x $\frac{10^{-3}g}{1 mg}$
611 mg = 611 x $10^{-3}$ g
Covert 611 x $10^{-3}$ g to µg.
611 x $10^{-3}$ g x $\frac{10^{6}µg}{1g}$
611 x $10^{-3}$ g = 611 x $10^{3}$ µg
So
611 mg = 611 x $10^{3}$ µg
611 mg = 6.11 x $10^{5}$ µg