Chemical & Ionic Equilibrium · JEE Main previous year questions

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2026 40 questions

Q552026 · 8 Apr 2026 · Shift 2
Consider the following reactions in which all the reactants and products are present in gaseous state $2 x y ⇌ x_{2} + y_{2} K_{1} = 2.5 \times 1 0^{5}$ $x y + \frac{1}{2} z_{2} ⇌ x y z K_{2} = 5 \times 1 0^{- 3}$ The value of $K_{3}$ for the equilibrium $\frac{1}{2} x_{2} + \frac{1}{2} y_{2} + \frac{1}{2} z_{2} ⇌ x y z$ is :
1. A. $2.5 \times 1 0^{- 3}$
2. B. $2.5 \times 1 0^{3}$
3. C. $1.0 \times 1 0^{- 5}$
4. D. $5 \times 1 0^{- 3}$
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Answer: C
Q752026 · 8 Apr 2026 · Shift 2· Numerical answer
Solid carbon, $CaO$ and $CaC O_{3}$ are mixed and allowed to attain equilibrium at $T K$ . $CaC O_{3} (s) ⇌ CaO (s) + C O_{2} (g) K_{p_{1}} = 0.08 atm$ $C (s) + C O_{2} (g) ⇌ 2 CO (g) K_{p_{2}} = 2 atm$ The partial pressure of $CO$ is ____ $\times 1 0^{- 1} atm$
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Answer: 4
Q562026 · 6 Apr 2026 · Shift 2
Given is a concentrated solution of a weak electrolyte $A_{x} B_{y}$ of concentration ' $c$ ' and dissociation constant ' $K$ '. The degree of dissociation is given by :
1. A. $[K \times c^{x + y - 1} x^{x} y^{y}]^{x + y}$
2. B. $(\frac{K}{c ^{x + y - 1} x ^{x} y ^{y}})^{\frac{1}{x + y}}$
3. C. $(\frac{c ^{x + y - 1} x ^{x} y ^{y}}{K})^{x + y}$
4. D. $(\frac{c ^{x + y - 1} x ^{x} y ^{y}}{K})^{\frac{1}{x + y}}$
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Answer: B
Q642026 · 6 Apr 2026 · Shift 2
' $x$ ' is the product which is obtained by the hydrolysis of prop-1-yne in the presence of mercuric sulphate under dilute acidic medium at $333 K$ . ' $y$ ' is the product which is obtained by the reaction of ethane nitrile with methyl magnesium bromide in dry ether followed by hydrolysis. IUPAC name of product obtained from ' $x$ ' and ' $y$ ' in the presence of barium hydroxide followed by heating is :
1. A.2-Methylpent-4-en-3-one
2. B.4-Methylpent-3-en-2-one
3. C.4-Methylpent-1-ene
4. D.2-Methylpent-3-one
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Answer: B
Q742026 · 6 Apr 2026 · Shift 2· Numerical answer
In a closed flask at $600 K$ , one mole of $X_{2} Y_{4 (g)}$ attains equilibrium as given below : $X_{2} Y_{4 (g)} ⇌ 2 XY_{2 (g)}$ At equilibrium, $75%$ $X_{2} Y_{4 (g)}$ was dissociated and the total pressure is $1 atm$ . The magnitude of $Δ_{r} G^{⊖}$ (in $kJ mol^{- 1}$ ) at this temperature is ________. (Nearest Integer) (Given : $R = 8.3 J mol^{- 1} K^{- 1}$ ; $ln 10 = 2.3$ , $lo g 2 = 0.3$ , $lo g 3 = 0.48$ , $lo g 5 = 0.69$ , $lo g 7 = 0.84$ )
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Answer: 8
Q552026 · 5 Apr 2026 · Shift 1
$M_{3} A_{2}$ is a sparingly soluble salt of molar mass $y g mol^{- 1}$ and solubility $x g L^{- 1}$ . The ratio of the molar concentration of the anion $(A^{3 -})$ to the solubility product of the salt is
1. A. $\frac{1}{54} \cdot \frac{y ^{4}}{x ^{4}}$
2. B. $\frac{y ^{5}}{108 x ^{4}}$
3. C. $108 \cdot \frac{x ^{5}}{y ^{5}}$
4. D. $\frac{1}{108} \frac{y ^{4}}{x ^{4}}$
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Answer: A
Q562026 · 5 Apr 2026 · Shift 1
Arrange the following resultant mixtures in increasing order of their $pH$ values A. $10 mL 0.2 M Ca(OH)_{2} + 25 mL 0.1 M HCl$ B. $10 mL 0.01 M H_{2} SO_{4} + 10 mL 0.01 M Ca(OH)_{2}$ C. $10 mL 0.1 M H_{2} SO_{4} + 10 mL 0.1 M KOH$ Choose the correct answer from the options given below:
1. A. $B < C < A$
2. B. $C < A < B$
3. C. $C < B < A$
4. D. $A < C < B$
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Answer: C
Q742026 · 5 Apr 2026 · Shift 1· Numerical answer
The values of pressure equilibrium constant recorded at different temperatures for the following equilibrium reaction have been given below $A(g) ⇌ B(g) + C(g)$ $\frac{1}{T} (K^{- 1}) 0.05 0.06 0.07 lo g_{10} K_{p} 3.5 2.5 1.5$ The magnitude of $\frac{Δ H ^{\circ}}{R}$ calculated from the above data is _______. (Nearest integer)
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Answer: 230
Q542026 · 5 Apr 2026 · Shift 2
Consider the following data for the reaction $X_{2} (g) + Y_{2} (g) ⇌ 2XY (g)$ at $600 K$ . The $Δ_{r} G^{⊖}$ (in $kJ mo l^{- 1}$ ) for the reaction is : $Compound XY (g) X_{2} (g) Y_{2} (g) Δ_{f} H_{600 K}^{⊖} (kJ mo l^{- 1}) 42880 S_{600 K}^{⊖} (J mo l^{- 1} K^{- 1}) 200140250$
1. A. $- 21000$
2. B. $- 10$
3. C. $- 1000$
4. D. $- 9.012$
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Answer: B
Q562026 · 5 Apr 2026 · Shift 2
The reaction $A (g) ⇌ B (g) + C (g)$ was initiated with the amount 'a' of $A (g)$ . At equilibrium it is found that the amount of $A (g)$ remaining is $(a - x)$ at a total pressure of $p$ . The equilibrium constant $Kp$ of the reaction can be calculated from the expression :
1. A. $\frac{x ^{2}}{a ^{2} + x ^{2}} \times p$
2. B. $\frac{x ^{2}}{a ^{2} - x ^{2}} \times p$
3. C. $\frac{a + x ^{2}}{x ^{2}} \times p$
4. D. $\frac{a ^{2} - x ^{2}}{x ^{2}} \times p$
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Answer: B
Q662026 · 5 Apr 2026 · Shift 2
1. A.Both Statement I and Statement II are true
2. B.Both Statement I and Statement II are false
3. C.Statement I is true but Statement II is false
4. D.Statement I is false but Statement II is true
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Answer: D
Q732026 · 5 Apr 2026 · Shift 2· Numerical answer
$20 g$ hemoglobin in a $1 L$ aqueous solution (A) at $300 K$ is separated from pure water by semi permeable membrane. At equilibrium the height of solution in a tube dipped in a solution (A) is found to be $80.0 mm$ higher than the tube dipped in water. The molar mass of hemoglobin is ____ $kg mo l^{- 1}$ . (Nearest integer) (Given : $g = 10 m s^{- 2}$ , $R = 8.3 kPa d m^{3} K^{- 1} mo l^{- 1}$ , $density of solution = 1000 kg m^{- 3}$ )
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Answer: 62
Q552026 · 4 Apr 2026 · Shift 1
At $T (K)$ , the equilibrium constant of $A_{2} (g) + B_{2} (g) ⇌ C (g)$ is $2.7 \times 1 0^{- 5}$ . What is the equilibrium constant for $\frac{1}{3} A_{2} (g) + \frac{1}{3} B_{2} (g) ⇌ \frac{1}{3} C (g)$ at the same temperature?
1. A. $(2.7 \times 1 0^{- 5})^{3}$
2. B. $6 \times 1 0^{- 2}$
3. C. $2.7 \times 1 0^{- 5}$
4. D. $3 \times 1 0^{- 2}$
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Answer: D
Q742026 · 4 Apr 2026 · Shift 1· Numerical answer
The $pH$ of a solution obtained by mixing $5 mL$ of $0.1 M$ $N H_{4} OH$ solution with $250 mL$ of $0.1 M$ $N H_{4} Cl$ solution is ____ $\times 1 0^{- 2}$ .(Nearest integer) Given: $p K_{b} (N H_{4} OH) = 4.74$ $lo g 2 = 0.30$ $lo g 3 = 0.48$ $lo g 5 = 0.70$
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Answer: 756
Q552026 · 4 Apr 2026 · Shift 2
$20 mL$ of a solution of acetic acid required $28.4 mL$ of $0.1 M$ $NaOH$ for its neutralization. A solution (X) was prepared by mixing $20 mL$ of the above acetic acid and $14.2 mL$ of $0.1 M$ $NaOH$ solution. What is the pH of the solution (X)? ( $p K_{a}$ value of acetic acid is $4.75$ ).
1. A.7.0
2. B.4.75
3. C.3.5
4. D.4.82
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Answer: B
Q672026 · 4 Apr 2026 · Shift 2
1. A.
2. B.
3. C.
4. D.
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Answer: C
Q682026 · 2 Apr 2026 · Shift 1
1. A. $P > Q > R$
2. B. $R > P > Q$
3. C. $R > Q > P$
4. D. $P > R > Q$
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Answer: A
Q752026 · 2 Apr 2026 · Shift 1· Numerical answer
At the transition temperature T, $A ⇌ B$ and $Δ G^{0} = 105 - 35 lo g T$ where A and B are two states of substance X. The transition temperature in $^{\circ} C$ when pressure is $1 atm$ is ____. (Nearest integer)
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Answer: 727
Q562026 · 2 Apr 2026 · Shift 2
At $2 5^{\circ} C$ , $20.0 mL$ of $0.2 M$ weak monoprotic acid $HX$ is titrated against $0.2 M$ $NaOH$ . The $pH$ of the solution (a) at the start of the titration (when $NaOH$ has not been added) and (b) when $10 mL$ of $NaOH$ is added respectively, are : Given : $K_{a} = 5 \times 1 0^{- 4}$ $p K_{a} = 3.3$ $α ≪ 1$
1. A.(a) 0.7, (b) 2.0
2. B.(a) 2.0, (b) 3.3
3. C.(a) 1.1, (b) 2.2
4. D.(a) 3.0, (b) 2.2
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Answer: B
Q572026 · 28 Jan 2026 · Shift 1
$Ph - CH = C H_{2} (PhCOO)_{2} HBr Product$ Consider the above reaction A. The reaction proceeds through a more stable radical intermediate. B. The role of peroxide is to generate $H^{∙}$ (Hydrogen radical). C. During this reaction, benzene is formed as a byproduct. D. 1-Bromo-2-phenylethane is formed as the minor product. E. The same reaction in absence of peroxide proceeds via carbocation intermediate. Identify the correct statements. Choose the correct answer from the options given below :
1. A.A & E Only
2. B.A, B & D Only
3. C.A, C & E Only
4. D.C, D & E Only
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Answer: C
Q662026 · 28 Jan 2026 · Shift 1
Consider a weak base ' B ' of $p K_{b} = 5.699$ . ' $x$ ' $mL$ of $0.02 M HCl$ and ' y ' $mL$ of $0.02 M$ weak base ' B ' are mixed to make $100 mL$ of a buffer of $pH 9$ at $2 5^{\circ} C$ . The values of ' $x$ ' and ' $y$ ' respectively are : [Given : $lo g 2 = 0.3010$ , $lo g 3 = 0.4771$ , $lo g 5 = 0.699$ ]
1. A. $x = 42.7, y = 57.3$
2. B. $x = 14.3, y = 85.7$
3. C. $x = 85.7, y = 14.3$
4. D. $x = 11.1, y = 88.9$
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Answer: B
Q732026 · 28 Jan 2026 · Shift 1· Numerical answer
Consider the dissociation equilibrium of the following weak acid $HA ⇌ H^{+} (aq) + A^{-} (aq)$ If the $pKa$ of the acid is $4$ , then the $pH$ of $10 mM$ $HA$ solution is ____ .(Nearest integer) [Given: The degree of dissociation can be neglected with respect to unity]
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Answer: 3
Q752026 · 28 Jan 2026 · Shift 1· Numerical answer
500 mL of 1.2 M KI solution is mixed with 500 mL of $0.2 M KMnO_{4}$ solution in basic medium. The liberated iodine was titrated with standard $0.1 M Na_{2} S_{2} O_{3}$ solution in the presence of starch indicator till the blue color disappeared. The volume (in L) of $Na_{2} S_{2} O_{3}$ consumed is _____ . (Nearest integer)
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Answer: 3
Q522026 · 28 Jan 2026 · Shift 2
The plot of $lo g_{10} K$ vs $\frac{1}{T}$ gives a straight line. The intercept and slope respectively are (where K is equilibrium constant).
1. A. $- \frac{Δ S ^{\circ} R}{2.303}, \frac{Δ H ^{\circ} R}{2.303}$
2. B. $- \frac{Δ H ^{\circ}}{2.303 R}, \frac{Δ S ^{\circ}}{2.303 R}$
3. C. $\frac{Δ S ^{\circ}}{2.303 R}, - \frac{Δ H ^{\circ}}{2.303 R}$
4. D. $\frac{2.303 R}{Δ H ^{\circ}}, \frac{2.303 R}{Δ S ^{\circ}}$
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Answer: C
Q512026 · 24 Jan 2026 · Shift 1
1. A.Statement I is false but Statement II is true
2. B.Statement I is true but Statement II is false
3. C.Both Statement I and Statement II are true
4. D.Both Statement I and Statement II are false
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Answer: B