Answer:
[tex]\boxed {\boxed {\sf 2.8 \ m }}[/tex]
Explanation:
The formula for molality is:
[tex]m=\frac{moles \ of \ solute}{kg \ of \ solvent}[/tex]
There are 0.210 moles of KBr and 0.075 kilograms of pure water.
[tex]moles= 0.210 \ mol \\kilograms = 0.075 \ kg[/tex]
Substitute the values into the formula.
[tex]m= \frac{ 0.210 \ mol }{0.075 \ kg}[/tex]
Divide.
[tex]m= 2.8 \ mol/kg= 2.8 \ m[/tex]
The molality is 2.8 moles per kilogram
