Buffer solutions and their pH — NEET & JEE Questions

Question 1 · difficulty L1 · recall

A buffer solution resists large changes in pH when

• A. small amounts of acid or base are added
• B. unlimited strong acid is added
• C. it contains only pure water
• D. all ions are removed

Question 2 · difficulty L2 · understanding

$\mathrm{K}_{\mathrm{a}}$ for $\mathrm{CH}_3 \mathrm{COOH}$ is $1.8 \times 10^{-5}$ and $\mathrm{K}_{\mathrm{b}}$ for $\mathrm{NH}_4 \mathrm{OH}$ is $1.8 \times 10^{-5}$. The $\mathrm{pH}$ of ammonium acetate solution will be _________.

Question 3 · difficulty L2 · understanding

The $$\mathrm{pH}$$ of an aqueous solution containing $$1 \mathrm{M}$$ benzoic acid $$\left(\mathrm{pK}_{\mathrm{a}}=4.20\right)$$ and $$1 \mathrm{M}$$ sodium benzoate is 4.5. The volume of benzoic acid solution in $$300 \mathrm{~mL}$$ of this buffer solution is _________ $$\mathrm{mL}$$. (given : $$\log 2=0.3$$)

Question 4 · difficulty L2 · understanding

$$600 \mathrm{~mL}$$ of $$0.01~\mathrm{M} ~\mathrm{HCl}$$ is mixed with $$400 \mathrm{~mL}$$ of $$0.01~\mathrm{M} ~\mathrm{H}_{2} \mathrm{SO}_{4}$$. The $$\mathrm{pH}$$ of the mixture is ___________ $$\times 10^{-2}$$. (Nearest integer) [Given $$\log 2=0.30$$ $$\log 3=0.48$$ $$\log 5=0.69$$ $$\log 7=0.84$$ $$\log 11=1.04]$$

Question 5 · difficulty L2 · understanding

Millimoles of calcium hydroxide required to produce 100 mL of the aqueous solution of pH 12 is $$x\times10^{-1}$$. The value of $$x$$ is ___________ (Nearest integer). Assume complete dissociation.

Question 6 · difficulty L2 · understanding

The dissociation constant of acetic acid is $$x\times10^{-5}$$. When 25 mL of 0.2 $$\mathrm{M~CH_3COONa}$$ solution is mixed with 25 mL of 0.02 $$\mathrm{M~CH_3COOH}$$ solution, the pH of the resultant solution is found to be equal to 5. The value of $$x$$ is ____________

Question 7 · difficulty L2 · understanding

$$\mathrm{K}_{\mathrm{a}}$$ for butyric acid $$\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COOH}\right)$$ is $$2 \times 10^{-5}$$. The $$\mathrm{pH}$$ of $$0.2 \,\mathrm{M}$$ solution of butyric acid is __________ $$\times 10^{-1}$$. (Nearest integer) [Given $$\log 2=0.30$$]

Question 8 · difficulty L2 · understanding

pH value of 0.001 M NaOH solution is ____________.

Question 9 · difficulty L2 · understanding

50 mL of 0.1 M CH 3 COOH is being titrated against 0.1 M NaOH. When 25 mL of NaOH has been added, the pH of the solution will be _____________ $$\times$$ 10 $$-$$2 . (Nearest integer) (Given : pK a (CH 3 COOH) = 4.76) log 2 = 0.30 log 3 = 0.48 log 5 = 0.69 log 7 = 0.84 log 11 = 1.04

Question 10 · difficulty L2 · understanding

The pH of a solution obtained by mixing 50 mL of 1 M HCl and 30 mL of 1 M NaOH is x $$\times$$ 10 $$-$$4 . The value of x is ____________. (Nearest integer) [log 2.5 = 0.3979]