How can 80ml of hcl solutions of ph 2 and 3 be obtained from a solution of 0.2m hcl? (hint: make 100ml solutions using 100ml volumetric flask)
pls chemistry pros answer this, i need the answer of this in less than 6 hours : ( i got an exam and me and my pals are having hard time with this question

Case 1: pH = 2.

1) find the molar concentration of H3O + or H+

pH = - log [H +] = 2 => [H+] = 10 ^-2 = 0.01 M

2) find the number of moles that will have 80 ml of a 0.01 M solution:

M = n /V => n = M * V = 0.01 M * 0.080 liter = 0.00080 moles

3) Find the volume of the 0.2 M solution that has 0.00080 moles of H+

 M = n / V => V = n / M = 0.00080 mol / 0.2 M = 0.004 liter = 4 ml.

That means that you can take 4 ml of the solution 0.2M HCl (which will contain 0.00080 moles of H+) and add water until complete 80 ml.  

You can verify: 0.00080 mol / 0.080 liter = 0.01 M

pH = log (1 / 0.01) = 2 .

Case 2: pH = 3.

1) concentration of H+

pH = - log [H+] = 3 => [H+] = 10^ -3 = 0.001

2) number of moles that will have 80 ml 0.001 M solution

M = n / V => n = M * V = 0.001M * 0.080 liter = 0.000080  moles

3) Volume of the 0.2 M solution that will contain 0.000080 moles

M = n / V => V = n / M = 0.000080 mol / 0.2 M = 0.0004 liter = 0.40 ml

Then, you can take 0.40 ml of 0.2 M HCl solution and add water until complete the 80 ml.

Ibelieve your answer is true 

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water