At 700c (1290f), what is the maximum solubility
(a) of cu in ag? (
b) of ag in cu?

In this exercise we have to calculate the maximum of each component in the solution:

a) 4%

b) 5%

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.

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(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.

that's what i got you can count the number of atoms