In winter, a European car must use substance A to put in the car boiler tank to prevent freezing. If we want to protect the car boiler tank from freezing until -10°C, what is the concentration of solution A in mol/dm³? (Kf of water = 1.86°C/m, molecular mass of A = 120, density of substance A = 1.2 g/cm³, and density of water = 1 g/cm³)
a. 0.5 mol/dm³
b. 1.0 mol/dm³
c. 1.5 mol/dm³
d. 2.0 mol/dm³