Answer:
(a) 4 %; (b) 5 %
Explanation:
We need a Cu-Ag phase diagram to answer these questions (see diagram). Yours may differ slightly from the one I used.
(a) Cu in Ag
The horizontal red line at 700 °C cuts the right-hand solvus at about 4 % Ag-96 % Cu.
At this point, copper is in equilibrium with the eutectic.
At 700 °C, the maximum solubility of Cu is about 4 % by mass.
(b) Ag in Cu
The horizontal red line at 700 °C cuts the left-hand solvus at about 5 % Cu-95 % Ag.
At this point, silver is in equilibrium with the eutectic.
At 700 °C, the maximum solubility of Ag is about 5 % by mass.
