Question

If all the following 4 compounds were sold at the same price , which would be cheapest for preparing an antifreeze solution for a car radiator?

(A) CH₃OH

(B) C₂H₅OH

(C) C₂H₄(OH)₂

(D) C₃H₅(OH)₃

Answer 1

m. wt of glycerine (C3H5(OH)3)=92

m. wt of ethylene glycol (C2H4(OH)2)=62

m.wt of ethanol (C2H5OH) = 46

m. wt of methanol (CH3OH)=32

now, depression in freezing point is
inversely proportional to m. wt.
therefore, methanol (CH3OH) has large depression in freezing point.

For preparing antifreezing solution for car radiator, compound having large depression in freezing point is more cheaper.

therefore,
A. methanol (CH3OH) is more cheaper.