where M1 is the concentration of the stock solution, V1 is the
volume of the stock solution, M2 is the concentration of the new solution and
V2 is its volume.
M1V1 = M2V2
40% x 30 L = 30% x V2
V2 = 40 L
Therefore, you will need to have 30 mL of the 40% acid solution
and 10 mL of distilled water. In mixing the two liquids, you should remember
that the order of mixing would be acid to water. So, you use a 40 mL volumetric flask . Put small amount of distilled water and add the 30 mL of HCl solution. Lastly, dilute with distilled water up to the mark.
Your answer would be D. As the circulatory system pumps oxygen rich blood through the body, and the respiratory system helps you to breath. Hope this helps!
