• question_answer
                    When a substance A reacts with water it produces a combustible gas B and a solution of substance C in water. When another substance D reacts with this solution of C, it also produces the same gas B on warming but D can produce gas B on reaction with dilute sulphuric acid at room temperature. ?A? imparts a deep golden yellow colour to a smokeless flame of bunsen burner A, B, C and D respectively are:

    A)                                                                                                                                                                                                                 \[Na,\,{{H}_{2}},\,NaOH,\,Zn\]

    B)                 \[K,\,{{H}_{2}},\,KOH,\,Al\]        

    C)                 \[Ca{{H}_{2}},\,Ca{{(OH)}_{2}},\,Sn\]     

    D)                 \[Ca{{C}_{2}},\,{{C}_{2}}{{H}_{2}},\,Ca{{(OH)}_{2}},\,Fe\]

    Correct Answer: A

    Solution :

                              Only Na gives golden colour to bunsen flame. So, A is Na. \[\underset{'A'}{\mathop{2Na}}\,+2{{H}_{2}}O\xrightarrow[{}]{{}}\underset{'C'}{\mathop{2NaOH}}\,+\underset{'B'}{\mathop{{{H}_{2}}}}\,\uparrow \] \[\underset{'D'}{\mathop{Zn}}\,+\underset{'C'}{\mathop{2NaOH}}\,\xrightarrow[{}]{{}}N{{a}_{2}}Zn{{O}_{2}}+\underset{'B'}{\mathop{{{H}_{2}}}}\,\uparrow \] \[\underset{'D'}{\mathop{Zn}}\,+dil.\,\,{{H}_{2}}S{{O}_{4}}\xrightarrow[{}]{{}}ZnS{{O}_{4}}+\underset{'B'}{\mathop{{{H}_{2}}}}\,\uparrow \]                 Na, produces golden yellow colour with smokeless flame of bunsen burner.

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