Final answer:
To determine the number of ghrelin molecules in 1 L of fasting person's blood with a concentration of 1.3 X 10⁻¹⁰ M, we multiply by Avogadro's number resulting in approximately 7.83 X 10¹³ molecules. The correct answer is a. 1.3 X 10⁻¹⁰ x 6.23 x 10²³.
Step-by-step explanation:
The concentration of the appetite-regulating hormone ghrelin is about 1.3 X 10⁻¹⁰ M in the blood of a fasting person. To find out how many molecules of ghrelin are in 1 L of blood, we use Avogadro's number, which is 6.023 X 10²³ molecules/mol. Multiplying the concentration by Avogadro's number gives us the total number of molecules in 1 L of blood.
Calculation:
1.3 X 10⁻¹⁰ mol/L * 6.023 X 10²³ molecules/mol = 7.8299 X 10¹³ molecules/L
Therefore, the correct option that represents the number of ghrelin molecules in 1 L of blood is a. 1.3 X 10⁻¹⁰ x 6.23 x 10²³, which is approximately 7.83 X 10¹³ molecules.