KVPY Sample Paper KVPY Stream-SX Model Paper-29

  • question_answer
    Which of the following, when mixed, will give a solution with pH > 7?

    A) 100 mL 0.1 M HCl+100mL 0.1 M KCl

    B) 100 mL 0.1M \[{{H}_{2}}S{{O}_{4}}\]+100 mL 0.1M NaOH

    C) 100 mL 0.1M\[{{\operatorname{CH}}_{3}}COOH\]+100mL 0.1M KOH

    D) 50 mL 0.1M HCl+50mL 0.1 M \[C{{H}_{3}}COONa\]

    Correct Answer: C

    Solution :

    [a] \[[{{H}^{+}}]=\frac{100\times 0.1}{200}=0.05,pH<7\]
    [b] Meq of \[{{\operatorname{H}}_{2}}S{{O}_{4}}=2\times 0.1\times 100=20\]
    Meq of \[NaOH = 0.1 \times  100 = 10\]
    Meq of excess \[{{\operatorname{H}}_{2}}S{{O}_{4}}=20-10=10;pH<7\]
    [c] \[{{\operatorname{CH}}_{3}}COOH+KOH\xrightarrow{{}}C{{H}_{3}}COOK+{{H}_{2}}O\]
    \[[Salt]=\frac{0.1\times 100}{200}=0.05\operatorname{M};pH>7\] due to hydrolysis of salt of weak acid with a strong base.
    [d] \[C{{H}_{3}}COONa+ HCl \xrightarrow{{}} C{{H}_{3}}COOH +NaCl\]
    \[[C{{H}_{3}}COOH]=\frac{0.1\times 50}{100}=0.05M,pH<7\]

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