NEETChemistryIonic Equilibrium
Match List-I with List-II for the pH of various equal-volume mixtures. [Given: pK _ a of weak acid HA = 4.0 , pK _ b of weak base BOH = 5.0 at 298 K ] List-I (Mixture) List-II (pH) (A) 0.1 M HA + 0.1 M NaA (I) 3.0 (B) 0.1 M HA + 1.0 M NaA (II) 4.0 (C) 1.0 M HA + 0.1 M NaA (III) 5.0 (D) 0.1 M BOH + 0.1 M BCl (IV) 9.0 Choose the correct answer from the options given below:
Options
- A(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
- B(A)-(II), (B)-(I), (C)-(III), (D)-(IV)
- C(A)-(II), (B)-(III), (C)-(I), (D)-(III)
- D(A)-(III), (B)-(II), (C)-(I), (D)-(IV)
Correct answer
A. (A)-(II), (B)-(III), (C)-(I), (D)-(IV)
Step-by-step solution
For acidic buffers, pH = pK _ a + ( [ Salt ] [ Acid ] ) (A) [ Salt ] = [ Acid ] = 0.1 M . pH = 4.0 + (1) = 4.0 (B) [ Salt ] = 1.0 M , [ Acid ] = 0.1 M . pH = 4.0 + ( 1.0 0.1 ) = 4.0 + (10) = 5.0 (C) [ Salt ] = 0.1 M , [ Acid ] = 1.0 M . pH = 4.0 + ( 0.1 1.0 ) = 4.0 - 1 = 3.0 For basic buffers, pOH = pK _ b + ( [ Salt ] [ Base ] ) (D) [ Salt ] = [ Base ] = 0.1 M . pOH = 5.0 + (1) = 5.0 pH = 14 - pOH = 14 - 5.0 = 9.0 Therefore, the correct matching is (A)-(II), (B)-(III), (C)-(I), (D)-(IV). Answer: (A)-(II), (B)-(III