Which aqueous solution has minimum freezing point?

Options

A. (a) `0.01M NaCl`
B. (b) `0.005M C_(2)H_(5)OH`
C. ( c) `0.005 M MgI_(2)`
D. (d) `0.005M MgSO_(4)`

Answer

A

Explanation

`C.P. prop (w)/(m xx V) (1- alpha-x alpha + y alpha)`
or `C.P. prop C xx (1-alpha+x alpha+ y alpha)`
for solute `A_(x), B_(y)`, `alpha` is degree of ionisation. Colligative properties are osmotic pressure, lowering in vapour pressure, elevation in b.pt. depression in f.pt.