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Salt Analysis question

2025 · 7 Apr · Shift 1 · Q5
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  5. /2025 · 7 Apr · Shift 1 · Q5

Salt Analysis question

2025 · 7 Apr · Shift 1 · Q5

JEE MainChemistrySalt AnalysisMCQ+4 / −1
Which of the following compounds is least likely to give effervescence of CO2\mathrm{CO}_2CO2​ in presence of aq. NaHCO3?\mathrm{NaHCO}_3 ?NaHCO3​?
  1. A
    JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Salt Analysis Question 4 English Option 1
  2. B
    JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Salt Analysis Question 4 English Option 2
  3. C
    JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Salt Analysis Question 4 English Option 3
  4. D
    JEE Main 2025 (Online) 7th April Morning Shift Chemistry - Salt Analysis Question 4 English Option 4
View written solutionFree

Correct answer: D

  1. Principle involved

    A compound will give effervescence of CO2\mathrm{CO_2}CO2​ with aqueous NaHCO3\mathrm{NaHCO_3}NaHCO3​ if it is more acidic than carbonic acid.

    The relevant reaction is: HA+NaHCO3→NaA+H2O+CO2↑\mathrm{HA + NaHCO_3 \rightarrow NaA + H_2O + CO_2\uparrow}HA+NaHCO3​→NaA+H2​O+CO2​↑

    So, compounds containing sufficiently acidic groups such as:

    • carboxylic acids,
    • strong phenols with electron-withdrawing groups,
    • mineral acids, are likely to produce CO2\mathrm{CO_2}CO2​.
  2. What is asked?

    We need the compound least likely to give effervescence with NaHCO3\mathrm{NaHCO_3}NaHCO3​.

    That means we should identify the option that is not acidic enough to liberate CO2\mathrm{CO_2}CO2​ from bicarbonate.

  3. Key chemical idea

    Ordinary phenols are weaker acids than carbonic acid and generally do not react with NaHCO3\mathrm{NaHCO_3}NaHCO3​ to release CO2\mathrm{CO_2}CO2​.

    On the other hand:

    • carboxylic acids do,
    • stronger acids do,
    • highly activated phenols (for example, with multiple nitro groups) may also do so.
  4. Issue with the given options

    The actual structures/options for A, B, C, and D are not visible in the prompt, so a direct option-by-option evaluation is not possible.

    However, based on the stored correct answer being D, the intended option DDD is most likely the compound that is least acidic among the choices (commonly an ordinary phenol or similar weak acid), and hence least likely to evolve CO2\mathrm{CO_2}CO2​ with aqueous NaHCO3\mathrm{NaHCO_3}NaHCO3​.

  5. Conclusion

    Therefore, the answer is: D\boxed{D}D​

    This is consistent with the rule that only acids stronger than carbonic acid liberate CO2\mathrm{CO_2}CO2​ from bicarbonate, while weaker acids generally do not.

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