7. To prepare 500~cm^{3} of 0.15 mol/dm³ sulphuric acid from a stock solution of 2.0~mol/dm^{3} sulphuric acid. The volume of stock solution required is (A)37~cm^{3} (B)37.5~cm^{3}(C)27.8~cm^{3}(D) 25.4~cm^{3}
To find the volume of stock solution required, we can use the formula:
C₁V₁ = C₂V₂
Where:
C₁ = concentration of the stock solution (2.0 mol/dm³)
V₁ = volume of the stock solution
C₂ = concentration of the final solution (0.15 mol/dm³)
V₂ = volume of the final solution (500 cm³)
Rearranging the formula, we get:
V₁ = (C₂ * V₂) / C₁
Substituting the given values:
V₁ = (0.15 mol/dm³ * 500 cm³) / 2.0 mol/dm³
V₁ = 37.5 cm³
Therefore, the volume of stock solution required is 37.5 cm³.
The answer is (B) 37.5 cm³.