When reacting 100 mL of 2 M HCl with 100 mL of 2 M NaOH,

how many milliliters of water should be produced?
(REM: Density of Water)

HCl + NaOH ==> NaCl + H2O

moles HCl = M x L = ??
moles NaOH = M x L = same number.
moles H2O produced = same number.
grams H2O = moles x molar mass.
Look up density of water at the temperature of the reaction and mass = volume x density. You know mass and density, solve for volume. You don't list a T; therefore, I assume the problem expects you to assume density H2O = 1.00 g/mL.