Phosphoric acid ionizes in three steps, with their ionization constant values \(\mathrm{K}_{\mathrm{a}_1}, \mathrm{~K}_{\mathrm{a}_2} \text { and } \mathrm{K}_{\mathrm{a}_3} \text {, }\)respectively, while \(K\) is the overall ionization constant. Which of the following statements are true for the ionization of phosphoric acid?
A. \(\log \mathrm{K}=\log \mathrm{K}_{\mathrm{a}_1}+\log \mathrm{K}_{\mathrm{a}_2}+\log \mathrm{K}_{\mathrm{a}_3}\)
B. \(\mathrm{H}_3 \mathrm{PO}_4\) is a stronger acid than \(\mathrm{H}_2 \mathrm{PO}_4^{-}\) and \(\mathrm{HPO}_4^{2-} .\)
C. \(\mathrm{K}_{a_1} >\mathrm{~K}_{\mathrm{a}_2}>\mathrm{K}_{\mathrm{a}_3} \)
D. \(\mathrm{K}_{\mathrm{a}_1}=\frac{\mathrm{K}_{\mathrm{a}_3}+\mathrm{K}_{\mathrm{a}_2}}{2}\)
Choose the correct answer from the options given below : 
1. B, C and D only 
2. A, B and C only 
3. A and B only 
4. A and C only
Subtopic:  Ionisation Constant of Acid, Base & Salt |
 57%
Level 3: 35%-60%
NEET - 2025
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For a weak acid HA, the percentage of dissociation is nearly 1% at equilibrium.
If the concentration of acid is 0.1 mol L-1, then the correct option for its Ka at the same temperature will be:
1. \(1 \times 10^{-4}\) 2. \(1 \times 10^{-6} \)
3. \(1 \times 10^{-5} \) 4. \(1 \times 10^{-3} \)
Subtopic:  Ionisation Constant of Acid, Base & Salt |
 68%
Level 2: 60%+
NEET - 2023
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