See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Acidic Strength Ordering **Evaluating each option:** **Option (A): $CH_3CO_2H > CH_3CO_3H$** - $CH_3CO_2H$ (acetic acid): $K_a \approx 1.8 \times 10^{-5}$ - $CH_3CO_3H$ (performic acid): $K_a \approx 3 \times 10^{-4}$ Wait — this appears reversed at first glance, but examining the notation: if $CH_3CO_3H$ means a carboxylic acid with peroxide functionality, it's actually **weaker** due to electron-withdrawing effects being less pronounced than the standard carboxyl. The standard interpretation makes acetic acid stronger. ✓ **Option (B): $H_2O > C_2H_5OH > NH_3 > HC \equiv CH > CH_2=CH_2 > CH_3-CH_3$** - Water ($K_a \approx 10^{-16}$) is much weaker than ethanol ($\approx 10^{-16}$) - Ammonia ($K_b$ scale, not $K_a$) cannot be compared directly - Alkenes and alkanes are extremely weak acids - **Incorrect ordering** — multiple violations ✗ **Option (C): $HCOOH > CH_3-COOH > PhCOOH$** - Formic acid: $K_a = 1.8 \times 10^{-4}$ - Acetic acid: $K_a = 1.8 \times 10^{-5}$ - Benzoic acid: $K_a = 6.3 \times 10^{-5}$ **Actual order:** $HCOOH > PhCOOH > CH_3COOH$ The phenyl group provides resonance stabilization of the conjugate base (more than the methyl group), making benzoic acid stronger than acetic acid. **Incorrect** ✗ **Answer: (A)** — It correctly orders two carboxylic acids by acidic strength.