can you check if I did the problems correctly? thanks!

Question

a soln of NaOH is prepared by dissolving 5.0g of NaOH in 500mL of water, the nadding additional water to make 1.0 L of soln. What is the pOH and pH of this soln?

[OH-]=(5g/40g)mol/1L
pOH=-log(1/8)=.90

[H3O+]=(1.0x10^-14)/(1/8)=8x10^-14
pH=-log(8x10^-14)=13.10

What is true about strong acids and bases?
*It is impossible to calculate pH from the hydroxide ion concentration
*pOH is not related to the proton concentration
*the concentration of hydroxide ions or proton is equal to the concentration of the substance dissolved
*pOH is equal to -pH

Statement 1 is wrong in saying that it is "impossible" I could also eliminate statement 4. I think either statement 2 or 3 is correct. Which one is it?

Answer 1

The pH of the NaOH solution is done correctly and you have the correct answer.
Problem 2.
Statement 1 definitely is not true.
Statement 2 definitely is not true (you just did that in the problem above).
Statement 3 is true.
Statement 4 definitely is not true for you used that in the problem above.