Answer:
10 mol/kg.
Step-by-step explanation:
Molality can be defined as the number of moles of solute divided by the mass of solvent.
Number of moles = mass/molar mass
= 25/25
= 1 mol.
Mass of solvent in kg = 100 g * 1 kg/1000 g
= 0.1 kg
Molality, m = 1/0.1
= 10 mol/kg.