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Equilibrium · Question 40

JEE Main 2025 (Online) 28th January Morning ShiftMCQEasy📈 Topic in 13% papers+4−1
1

A weak acid HA has degree of dissociation x. Which option gives the correct expression of (pH - pKa)?

  1. ( 1-xx )
  2. 0
  3. (1+2x)
  4. ( x1-x )

Answer

(4) ( x1-x )

Solution

HA H+ + A-

At equilibrium: [HA] = c(1-x), [A-] = cx

Ka = [H+][A-][HA]

Ka = [H+] + [A-][HA]

pH = pKa + [A-][HA]

pH - pKa = cxc(1-x) = ( x1-x )

Answer: (4)

JEE Main 2025 (Online) 28th January Morning Shift

Keep practising — Equilibrium

2

Ice and water are placed in a closed container at a pressure of 1 atm and temperature 273.15 K. If pressure of the system is increased 2 times, keeping temperature constant, then identify correct observation from following

  1. Liquid phase disappears completely.
  2. The amount of ice decreases.
  3. The solid phase (ice) disappears completely.
  4. Volume of system increases.
JEE Main 2025 (Online) 28th January Morning Shift
3

Arrange the following in increasing order of solubility product : Ca(OH)2, AgBr, PbS, HgS

  1. PbS < HgS < Ca(OH)2 < AgBr
  2. HgS < AgBr < PbS < Ca(OH)2
  3. HgS < PbS < AgBr < Ca(OH)2
  4. Ca(OH)2 < AgBr < HgS < PbS
JEE Main 2025 (Online) 28th January Evening Shift

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