For a given number of moles of solute, why do ionic substances have a larger effect on the freezing and boiling points of solvents than do non-ionic or molecular substances?

yes the answer is total mass in unchanged   : )

if the temperature drops and becomes cool

then the atmosphere can be freezing as the water vapor in the air is at maximum (100%) and can be severely cold

also can be snowing lightly as the moisture in the air will start to solidify

and btw this is not chemistry but