Which of the following mixture gives a buffer solution with pH = 9.25
Given : $p K_{b} (N H_{4} O H)$ = 4.75 [2026]

Question

Which of the following mixture gives a buffer solution with pH = 9.25 ?
Given : $p K_{b} (N H_{4} O H)$ = 4.75 [2026]

Smart Achievers · Accepted Answer

(2)

$pOH = p K_{b} + \log (\frac{Salt}{Base})$

$4.75 = 4.75 + \log (\frac{Salt}{Base})$

$Millimoles of [Salt] = millimoles of [Base]$

$Option (D):$

$\begin{matrix} {NH}_{4} OH & + & HCl & \to & {NH}_{4} Cl & + & H_{2} O \\ 0.2 M, 0.5 L & 0.1 M, 0.5 L \\ 100 mmole & 50 mmole \\ 50 mmole & - & 50 mmole \end{matrix}$

$Millimoles of {NH}_{4} OH = millimoles of {NH}_{4} Cl$

Solution

Q.
Which of the following mixture gives a buffer solution with pH = 9.25
Given : $p K_{b} (N H_{4} O H)$ = 4.75 [2026]

1 $0.4 M N H_{4} O H (1 L) + 0.1 M H C l (1 L)$

2 $0.2 M N H_{4} O H (0.5 L) + 0.1 M H C l (0.5 L)$

3 $0.2 M N H_{4} O H (0.4 L) + 0.1 M H C l (1 L)$

4 $0.5 M N H_{4} O H (0.2 L) + 0.2 M H C l (0.5 L)$

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Solution

Q. Which of the following mixture gives a buffer solution with pH = 9.25 Given : pKb(NH4OH) = 4.75 [2026]

1 0.4 M NH4OH (1 L)+0.1 M HCl (1 L)

2 0.2 M NH4OH (0.5 L)+0.1 M HCl (0.5 L)

3 0.2 M NH4OH (0.4 L)+0.1 M HCl (1 L)

4 0.5 M NH4OH (0.2 L)+0.2 M HCl (0.5 L)