CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2011

  • question_answer
    Be and\[Al\]exhibit diagonal relationship. Which of the following statements about them is/are not true? I. Both react with\[HCl\]to liberate\[{{H}_{2}}\] II. They are made passive by\[HN{{O}_{3}}\] III. Their carbides give acetylene on treatment with water IV. Their oxides are amphoteric

    A)  III and IV         

    B)         I and III

    C)  I only                   

    D)         II and III

    E)  III only

    Correct Answer: E

    Solution :

    (i)\[Be\]and\[Al\]both react with\[HCl\]to liberate \[{{H}_{2}}\]. \[Be+2HCl\xrightarrow[{}]{{}}BeC{{l}_{2}}+{{H}_{2}}\uparrow \] \[2Al+6HCl\xrightarrow[{}]{{}}2AlC{{l}_{3}}+3{{H}_{2}}\uparrow \] (ii) Be renders passive with cone.\[HN{{O}_{3}}\]and so does not react. Cone.\[HN{{O}_{3}}\]is strong oxidizing agent and forms very thin layer of oxide on the surface of metal. Similarly,\[Al\] become passive in cone.\[HN{{O}_{3}}\]due to formation of oxide layer on the surface. (iii) Their carbides gives methane on treatment with water. \[B{{e}_{2}}C+4{{H}_{2}}O\xrightarrow[{}]{{}}2Be{{(OH)}_{2}}+C{{H}_{4}}\] \[A{{l}_{4}}{{C}_{3}}+12{{H}_{2}}O\xrightarrow[{}]{{}}4Al{{(OH)}_{3}}+3C{{H}_{4}}\] (iv) Their oxides,\[BeO\]and\[A{{l}_{2}}{{O}_{3}}\]are amphoteric.


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