The answer is 22.02 meters
40cm is 20% of 2M
40cm is 400mm
40cm
40cm
Amount of HCl is 500cm^3 of .8M HCl = .8 x 500/1000 = 0.4 mol. Volume of 10M acid to give 0.4 mol = .4/10 = 0.04dm^3 = 40cm^3 Add 500 - 40 = 460 cm^3 of water. Caution : 10M HCl is highly corrosive and should be handled with care.
40cm times 40cm times 40cm equals 64,000cm. The volume of the cube is 64,000cm cubed or 0.064m cubed.
40
The perimeter is 40cm
10M 10M 10M
48,000 cubic cm
circumference = pi*40cm