Freezing point depression is a colligative property.
The formula that rules it is:
ΔT f = Kf * m
Where m is the molality of the solution => m = moles of solute / Kg of solvent
=> m = 0.31 mol / 0.175 kg = 1.771 m
And kf = 1.86 °C/m
=> ΔTf = 1.771 m * 1.86 °C / m = 3.3 °C
=> Freezing point of the solution = normal freezing point of water - 3.3 °C = 0 - 3.3°C = - 3.3°C.
Answer: -3.3 °C
<h2>Answer with Explanation </h2>
The energy transformation involved in heating soup in microwaves occurs due to microwave radiation. The radiant energy which also known as heat energy in the microwave causes the water molecules in the soup to gain kinetic energy. Hence, the molecules collide with each other more often causing the soup to heat up in form of waves that are built within the microwave. This is also the reason it is termed as mircowave due to release of waves.