Questions

Fog will form if the air temperature drops below the dew point, which is the capacity of the air to hold moisture in suspension. If the temperature drop far enough the moisture content will exceed saturation point, causing it to form visible water vapour.

It happens in the early mornings or late after noons.

The atmospheric pressure at the surface of the Earth is due to gravitational pull of the earth and is about 14.7 psi.

That means that the weight of a column of air which has a cross section of 1 square inch and which stretches from the surface of the Earth to space is 14.7 pounds. 

∆Tf = kf.m 

for ethylene glycol in aq. solution

 $$\begin{gathered} ∆Tf = kf wmol.wt × 1000wt. of solvent \\ 6 = 1.86 x w x 100062 x 4000 \end{gathered}$$

=> w = 800 g

So, the weight of solute should be more than 800 g.