NEET Sample Paper NEET Sample Test Paper-81

  • question_answer
    A black compound of manganese reacts with a halogen acid to give greenish yellow gas. When excess of this gas reacts with \[N{{H}_{3}}\], an unstable trihalide is formed. In this process the oxidation state of nitrogen changes from

    A)  -3 to +3                      

    B)  -3 to zero

    C)  -3 to + 5                     

    D)  0 to -3

    Correct Answer: A

    Solution :

    \[\underset{\begin{smallmatrix}  manganese \\  oxide(black)I \end{smallmatrix}}{\mathop{\operatorname{Mn}{{O}_{2}}}}\, + {{N}_{2}}S{{O}_{4}} + 2HCl\,\,\xrightarrow{{}}\,\,MnS{{O}_{4}}\] \[+2{{H}_{2}}O\underset{\begin{smallmatrix}  chlorine\,\,gas \\  (greenish\,\,yellow) \end{smallmatrix}}{\mathop{+C{{l}_{2}}}}\,\] \[\underset{ammonia}{\mathop{N{{H}_{3}}}}\,+3C{{l}_{2}}\xrightarrow{{}}\underset{\begin{smallmatrix}  Nitrogen\,\,trichloride \\  (unstable\,\,and\,\,explosive) \end{smallmatrix}}{\mathop{NC{{l}_{3}}+3HCl}}\,\] The oxidation state of N in \[N{{H}_{3}}\] is -3 while in \[NC{{l}_{3}}\] it is +3. Hence, in given process, oxidation state of nitrogen changed from -3 to +3.


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