question_answer

0.5 molal solution of ethylene glycol in water is used as coolant in car. If the freezing point depression constant of water is\[1.86{}^\circ C\]per mol, the mixture will freeze at

A) \[0.93{}^\circ C\]                             

B) \[-\text{ }0.93{}^\circ C\]

C)  \[1.86{}^\circ C\]            

D) \[-\text{ }1.86{}^\circ C\]                  \[\Rightarrow \]\[\Delta {{T}_{f}}={{k}_{f}}\times m\] \[=1.86\times 0.5=0.93{}^\circ C\] \[\therefore \] \[\Delta {{T}_{f}}=T_{f}^{o}-{{T}_{f}}\] \[\therefore \]  \[{{T}_{f}}=T_{f}^{o}-\Delta {{T}_{f}}=0-0.93=-{{0.93}^{o}}C\]