Question

Which of the following will not be soluble in sodiumhydrogen carbonate?

• A. Benzoic acid
• B. o-Nitrophenol
• C. Benzenesulphonic acid
• D. 2,4,6-trinitrophenol

Answer 1

The Correct Option is B

To determine which of the given compounds is not soluble in sodium hydrogen carbonate (NaHCO₃), we must understand the chemical nature of each compound.

1. Benzoic acid: Benzoic acid is a weak acid (organic acid) and typically reacts with sodium hydrogen carbonate, a weak base, to form soluble sodium benzoate and carbon dioxide. Thus, it is soluble in NaHCO₃.
2. o-Nitrophenol: o-Nitrophenol is a phenolic compound which is generally less acidic compared to carboxylic acids like benzoic acid. Because its acidity is not strong enough to react with NaHCO₃, it is not soluble in sodium hydrogen carbonate.
3. Benzenesulphonic acid: Benzenesulphonic acid is a strong acid and will readily react with sodium hydrogen carbonate to form a soluble salt and release CO₂. Therefore, it is soluble.
4. 2,4,6-Trinitrophenol (Picric acid): This is a very strong acid due to the electron-withdrawing effects of the nitro groups. It can easily react with sodium hydrogen carbonate to give a soluble salt. Therefore, it is soluble in NaHCO₃.

Based on the above analysis, o-Nitrophenol does not react with sodium hydrogen carbonate sufficiently due to its weaker acidic nature compared to the other given compounds, making it insoluble. Therefore, the correct answer is o-Nitrophenol.