Question

What is its mass in mg? Express your answer using two significant figures. V Αφ ? mg m = t

Answer 1

No of moles = no of given atoms/ Avogadro's number

= 2.1 x 10¹⁷/ 6.022 x 10²³

= 3.487 x 10^-7 moles

One of sucrose weighs 342.3 g

Mass of given number of moles = molar mass x no of moles

= 342.3 x 3.487 x 10^-7 g

= 1193.6 x 10^-7 g

= 0.0001194 g

now since this value is in grams and the answer is to be submitted in milligrams, therefore it is converted to milligrams

mass = 0.0001194 x 1000

= 0.11936

since, two significant digits are required thus the final answer is rounded to 2 significant digits.

Mass in two significant figures and miligram = 0.12 mg