• # question_answer Oleum is a mixture of A) ${{H}_{2}}{{S}_{2}}{{O}_{3}}+S{{O}_{2}}$          B) ${{H}_{2}}S{{O}_{4}}+S{{O}_{3}}$C) ${{H}_{2}}S{{O}_{4}}+S{{O}_{2}}$  D) ${{H}_{2}}S{{O}_{4}}+S{{O}_{3}}$

${{H}_{2}}{{S}_{2}}{{O}_{7}}$is oleum. It is formed by dissolving $S{{O}_{3}}$in${{H}_{2}}S{{O}_{4}}$which upon dilution gives two molecules of ${{H}_{2}}S{{O}_{4}}.$ Hence the correct option is [b].