The element whose percentage composition in an organic compound can be determined by Carius method is

' $x$ ' mg of an organic compound was analysed by Kjeldahl method. The ammonia evolved was absorbed in 50 mL of $0.5 \mathrm{M} \mathrm{H}_2 \mathrm{SO}_4$. The unused acid required 60 mL of 0.5 M NaOH solution for complete neutralisation. If the percentage of nitrogen in the compound is 56 , the value of $x$ is

A mixture of substances $A, B, C, D$ is subjected to column chromatography. The degree of adsorption is the order of $D>B>C>A$. The column is eluted with suitable solvent. Identify the correct statement with respect to separation of mixture