Q51. Molarity (M) of an aqueous solution containing $x$ g of anhyd. $\mathrm { CuSO } _ { 4 }$ in 500 mL solution at $32 ^ { \circ } \mathrm { C }$ is $2 \times 10 ^ { - 1 } \mathrm { M }$. Its molality will be $\_\_\_\_$ $\times 10 ^ { - 3 } \mathrm {~m}$. (nearest integer). [Given density of the solution $= 1.25 \mathrm {~g} / \mathrm { mL }$ ]