Answer:
6.52×10²⁰ molecules.
Explanation:
We'll begin by converting 210 mg of caffeine to grams (g). This can be obtained as follow:
Recall:
1 mg = 1×10¯³ g
Therefore,
210 mg = 210 mg / 1 mg × 1×10¯³ g
210 mg = 0.21 g
Therefore, 210 mg of caffeine is equivalent to 0.21 g of caffeine.
Finally, we shall determine the number of molecules in 0.21 g of caffeine as follow:
194 g of caffeine contains 602×10²³ molecules.
Therefore, 0.21 g of caffeine will contain = (0.21 × 602×10²³)/194 = 6.52×10²⁰ molecules.
Therefore 0.21 g contains 6.52×10²⁰ molecules.
Thus, we can say that 210 mg (i.e 0.21g) of caffeine contains 6.52×10²⁰ molecules.
