Giả sử mỗi quặng có 100 gam.

a)

\( \to {m_{CuFe{S_2}}} = 100.6\%  = 6{\text{ gam}}\)

\( \to {n_{CuFe{S_2}}} = \frac{6}{{64 + 56 + 32.2}} = 0,0326{\text{ mol = }}{{\text{n}}_{Cu}}\)

\( \to \% {m_{Cu}} = \frac{{0,0326.64}}{{100}} = 2,086\% \)

Đây là quặng trung bình

b)

\({m_{C{u_2}S}} = 100.4\%  = 4{\text{ gam}}\)

\( \to {n_{C{u_2}S}} = \frac{4}{{64.2 + 32}} = 0,025{\text{ mol}}\)

\( \to {n_{Cu}} = 2{n_{C{u_2}S}} = 0,05{\text{ mol}}\)

\( \to \% {m_{Cu}} = \frac{{0,05.64}}{{100}} = 3,2\% \)

Đây là quặng giàu.

c)

Ta có: 

\({n_{CuC{O_3}.Cu{{(OH)}_2}}} = 100.5\%  = 5{\text{ gam}}\)

\( \to {n_{CuC{O_3}.Cu{{(OH)}_2}}} = \frac{5}{{64 + 60 + 64 + 34}} = 0,0225{\text{ mol}}\)

\( \to {n_{Cu}} = 2{n_{CuC{O_3}.Cu{{(OH)}_2}}} = 0,0225.2 = 0,045{\text{ mol}}\)

\( \to \% {m_{Cu}} = \frac{{0,045.64}}{{100}} = 2,88\% \)