Answer: The mass of the substance is 20 g
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.
[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]
where,
n = moles of solute
[tex]V_s[/tex] = volume of solution in ml = 250 ml [tex](1cm^3=1ml)[/tex]
moles of [tex]NaOH[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{xg}{40g/mol}[/tex]
Now put all the given values in the formula of molality, we get
[tex]2=\frac{x\times 1000}{40\times 250}[/tex]
[tex]x=20g[/tex]
Therefore, the mass of the substance is 20 g
