Answer:
1, 2, and 3 are true.
Explanation:
The Henderson-Hasselbalch equation is:
pH = pka + log₁₀ [tex]\frac{[A^-]}{[HA]}[/tex]
pH = pka + log₁₀ [tex]\frac{[A^-]}{[HA]}[/tex]
If you know pH and pka:
10^(pH-pka) = [tex]\frac{[A^-]}{[HA]}[/tex]
The ratio will be: 10^(pH-pka)
pH = pka + log₁₀ [tex]\frac{[A^-]}{[HA]}[/tex]
0 = log₁₀ [tex]\frac{[A^-]}{[HA]}[/tex]
10^0 = [tex]\frac{[A^-]}{[HA]}[/tex]
1 = [tex]\frac{[A^-]}{[HA]}[/tex]
As ratio is 1, [conjugate base] = [acid] in solution.
pH = pka + log₁₀ [tex]\frac{[A^-]}{[HA]}[/tex]
If pH >> pKa, 10^(pH-pka) will be >> 1, that means that you have more [A⁻] than [HA]
pH = pka + log₁₀ [tex]\frac{[A^-]}{[HA]}[/tex]
If pH << pKa, 10^(pH-pka) will be << 1, that means that you have more [HA] than [A⁻]
I hope it helps!