Passage V
When a mixture is at equilibrium, no net phase changes occur. Figure 1 shows the phases of the metals gold (Au )and thallium (TI) present in various Au-TI mixtures at different temperatures and at equilibrium. The Au-TI mixtures contain only Au and Tl, so an Au-TI mixture that contains 60% Au will contain 40% Tl, and 100 g of this mixture will contain 60 g of Au and 40 g of Tl.
A cooling curve shows how the phases of the metals in the mixture change as it cools over time. Figure 2 shows a cooling curve for an Au-TI mixture containing 58% Au. Figure 2 also explains how Figure 1 is related to Figure 2.
29. According to Figure 1, at equilibrium, the lowest temperature at which an Au-TI mixture containing 90% Au will be completely liquid is closest to which of the following?
Your Answer is
Correct Answer is D
Explanation
Look at figure 1, when the abscissa is 90%, all mixtures are liquid corresponding to Region I. When the abscissa is 90% and the ordinate temperature is above 850°C, it belongs to Region I, so the D option 950°C is in line