CHEMISTRY
posted by TIANDRA .
1) An NaOH solution of unknown concentration is titrated with HCl.
51.9 mL of 0.400 mol/L HCl will neutralize 75.0 mL of the NaOH.
What is the concentration of the NaOH solution ? Record your answer in decimal notation.
I think the answer is 0.277 mol/L. is that right?
2)An NaOH solution of unknown concentration is titrated with HCl.
33.0 mL of 0.250 mol/L HCl will neutralize 50.0 mL of the NaOH.What is the concentration of the NaOH solution ?Record your answer in decimal notation.
I think the answer is 0.165 mol/L. is that right?
3) A basic solution of known concentration is titrated with a strong acid.
28.5 mL of 0.35 mol/L acid is used to neutralize a 0.30 mol/L base.What volume, in millilitres, of base will be neutralized ?Record your answer in decimal notation.
I am unsure of this one. Please help!
4) A basic solution of known concentration is titrated with a strong acid.
24.1 mL of 0.30 mol/L acid is used to neutralize a 0.10 mol/L base.What volume, in millilitres, of base will be neutralized ?Record your answer in decimal notation. Also unsure of this one. Please Help!

1 and 2 are correct.
#3. Technically, the problem SHOULD give you enough information to know if this is a 1:1 reaction or some other kind. It doesn't so I assume we assume it is 1:1; i.e., HA + BOH ==> BA + H2O
moles acid = M x L = ?
moles base = moles acid
M base = moles/L soln
You have M and moles, solve for L and convert to mL.
#4.
See my note for #3. This one is worked the same as #3 and we must make the same assumption. 
I still don't understand. Capital M x L

M = molarity
L = liter
molarity is moles/L; therefore, moles = M x L.