Practical Organic Chemistry

In the estimation of element \(\mathrm{X}\) in an organic compound, \(0.8 \mathrm{~g}\) of the compound containing \(\mathrm{X}\) was heated with fuming \(\mathrm{HNO}_3\) and the cooled product was treated with barium chloride. The mass of barium sulphate precipitated was \(1.2 \mathrm{~g}\). What is the percentage of element \(\mathrm{X}\) and what is the formula of the violet-coloured compound formed when Lassaigne's extract of the organic compound is treated with sodium nitroprusside?