The molal depression constant for water is 1.86$°$C. The freezing point of a 0.05-molal solution of a non-electrolyte in water is

Explanation

To calculate the freezing point depression, we use the formula:

ΔT_f = K_f × m

• ΔT_f is the freezing point depression
• K_f is the molal depression constant (given as 1.86°C for water)
• m is the molality of the solution (given as 0.05 molal)

Substituting the given values: f = 1.86 °C × 0.05 molal = 0.093 °C

Since the freezing point depression is negative (the solution freezes at a lower temperature than pure water), the freezing point will decrease by 0.093°C.

Thus, the new freezing point of the solution is:

0°C - 0.093°C = -0.093°C

Final Answer

So, the correct answer is: -0.093°C