Which one is more concentrated 1 molar NaOH or 1 molal NaOH aqueous solution? Explain?
Both solutions are dilute enough that they have the same concentrations within the uncertainty of measurement.
Let's calculate the percent by mass of each solution.
A 1 mol/kg
A 1 mol/L
The density of the solution is 1.04 g/mL.
Thus, both solutions have effectively the same concentration.