When hno2 is dissolved in water it partially dissociates according to the equation hno2⇌h++no−2. a solution is prepared that contains 4.000 g of hno2 in 1.000 kg of water. its freezing point is found to be -0.1692 ∘c calculate the fraction of hno2 that has dissociated.

The degree of dissociation is 1

thus the fraction dissociated is one

Explanation:

The depression in freezing point is a colligative property and depends upon the number of solute particles present in the solution.

The relation between depression in freezing point and molality is:

For water

Kf=1.86 °C/m

Where

i= Van't Hoff factor

For electrolytes the i depends upon on the extent of dissociation

i = αn + (1 - α)

Where

α = is degree of dissociation

Let us put the values

Putting value:

the answer to your question is c