Here is an image of the periodic table. Hope this helps.
Given that 1 micrometer or micron (um) is equivalent by definition to 1 x 10^-6 m, this means that 1 square micron (um^2) is equivalent to (1 x 10^-6)^2 m^2, or 1 x 10^-12 m^2.
(2.60 um^2) * (1 x 10^-12 m^2 / 1 um^2) = 2.60 x 10^-12 m^2
Therefore the layer of graphene covers an area of 2.60 x 10^-12 m^2.
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Answer:
SAMPLE A - pure substance.
SAMPLE B - homogeneous mixture.
SAMPLE C - heterogeneous mixture.
Explanation:
The molar mass of aluminum sulftae is 342.14 g/mol.
Since the subscript shows that there are 3 sulfurs within the substance, the total mass of sulfur is 96.21g/mol
Now take the mass of the sulfur and divide it by the molar mass of aluminum sulfate, then multiply by 100:
(96.21/342.15)(100) = 28.1% mass composition of sulfate