Answer:
7.826×10^14 molecules of ghrelin
Explanation:
Molarity of ghrelin = number of moles of ghrelin/volume of blood
number of moles of ghrelin = Molarity of ghrelin × volume of blood = 1.3×10^-9 × 1 = 1.3×10^-9 moles
From Avogadro's law
1 mole of a substance (ghrelin) contains 6.02×10^23 molecules
1.3×10^-9 moles of ghrelin contains 1.3×10^-9 × 6.02×10^23 = 7.826×10^14 molecules of ghrelin
