For a solution, the number of moles of solute is given by which formula when concentration c is in mol/L and volume V is in L?

• A. n = c * V
• B. n = c / V
• C. n = V / c
• D. n = c + V

Answer: (A)

The number of moles in a solution is found from how concentration and volume relate: concentration tells you how much solute sits in each unit of volume, so c = n / V. Rearranging gives n = c × V. With c in mol/L and V in L, the units multiply to mol, as expected for n. For example, 0.60 mol/L in 4.0 L contains 0.60 × 4.0 = 2.4 moles. The other simple algebraic options would not produce the correct units or meaning for n.