If \(250 \mathrm{~cm}^3\) of a saturated solution of potassium trioxonitrate \((\mathrm{V})\) at \(30^{\circ} \mathrm{C}\) produced \(3.4 \mathrm{~g}\) of the dry salt, calculate the solubility of the salt at \(30^{\circ} \mathrm{C}\) \((\mathrm{K}=39, \mathrm{~N}=14, \mathrm{O}=16)\)
A. \(0.112\) mol.dm \({ }^3\) B. \(0.118 \mathrm{~mol}^2 \mathrm{dm}^3\) C. \(0.124 \mathrm{~mol}^{\mathrm{dm}}{ }^3\) D. \(0.134\) mol. \(\mathrm{dm}^3\)
