Chemical & Ionic Equilibrium · JEE Main previous year questions

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2023 40 questions

Q832023 · 30 Jan 2023 · Shift 1· Numerical answer
$600 mL$ of $0.01 M$ $HCl$ is mixed with $400 mL$ of $0.01 M$ $H_{2} SO_{4}$ . The pH of the mixture is ___________ $\times 1 0^{- 2}$ . (Nearest integer) $[Given lo g 2 = 0.30$ $lo g 3 = 0.48$ $lo g 5 = 0.69$ $lo g 7 = 0.84$ $lo g 11 = 1.04]$
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Answer: 186
Q822023 · 29 Jan 2023 · Shift 1· Numerical answer
Millimoles of calcium hydroxide required to produce 100 mL of the aqueous solution of pH 12 is $x \times 1 0^{- 1}$ . The value of $x$ is ____ (Nearest integer). Assume complete dissociation.
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Answer: 5
Q872023 · 29 Jan 2023 · Shift 1· Numerical answer
Water decomposes at 2300 K $H_{2} O (g) \to H_{2} (g) + \frac{1}{2} O_{2} (g)$ The percent of water decomposing at 2300 K and 1 bar is ____ (Nearest integer). Equilibrium constant for the reaction is $2 \times 1 0^{- 3}$ at 2300 K.
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Answer: 2
Q882023 · 29 Jan 2023 · Shift 1· Numerical answer
Consider the following reaction approaching equilibrium at $2 7^{\circ} C$ and 1 atm pressure $A + B k_{r} = 1 0^{2} ⇌ k_{f} = 1 0^{3} C + D$ The standard Gibb's energy change $(Δ_{r} G^{θ})$ at $2 7^{\circ} C$ is $(-)$ ____ $kJ mo l^{- 1}$ (Nearest integer). (Given : $R = 8.3 J K^{- 1} mo l^{- 1}$ and $ln 10 = 2.3$ )
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Answer: 6
Q732023 · 29 Jan 2023 · Shift 2
An indicator 'X' is used for studying the effect of variation in concentration of iodide on the rate of reaction of iodide ion with $H_{2} O_{2}$ at room temp. The indicator 'X' forms blue coloured complex with compound 'A' present in the solution. The indicator 'X' and compound 'A' respectively are :
1. A.Methyl orange and $H_{2} O_{2}$
2. B.Methyl orange and iodine
3. C.Starch and $H_{2} O_{2}$
4. D.Starch and iodine
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Answer: D
Q832023 · 29 Jan 2023 · Shift 2· Numerical answer
At $298 K$ $N_{2} (g) + 3 H_{2} (g) ⇌ 2N H_{3} (g), K_{1} = 4 \times 1 0^{5}$ $N_{2} (g) + O_{2} (g) ⇌ 2NO (g), K_{2} = 1.6 \times 1 0^{12}$ $H_{2} (g) + \frac{1}{2} O_{2} (g) ⇌ H_{2} O (g), K_{3} = 1.0 \times 1 0^{- 13}$ Based on above equilibria, then equilibrium constant of the reaction, $2N H_{3} (g) + \frac{5}{2} O_{2} (g) ⇌ 2NO (g) + 3 H_{2} O (g)$ is ____ $\times 1 0^{- 33}$ (Nearest integer).
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Answer: 4
Q742023 · 25 Jan 2023 · Shift 1
Reaction of thionyl chloride with white phosphorus forms a compound [A], which on hydrolysis gives [B], a dibasic acid. [A] and [B] are respectively :
1. A. $P_{4} O_{6}$ and $H_{3} P O_{3}$
2. B. $POC l_{3}$ and $H_{3} P O_{4}$
3. C. $PC l_{5}$ and $H_{3} P O_{4}$
4. D. $PC l_{3}$ and $H_{3} P O_{3}$
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Answer: D
Q822023 · 25 Jan 2023 · Shift 1· Numerical answer
A litre of buffer solution contains 0.1 mole of each of $N H_{3}$ and $N H_{4} Cl$ . On the addition of 0.02 mole of HCl by dissolving gaseous HCl, the pH of the solution is found to be ____ $\times 1 0^{- 3}$ (Nearest integer) [Given : $p K_{b} (N H_{3}) = 4.745$ $lo g 2 = 0.301$ $lo g 3 = 0.477$ $T = 298 K$ ]
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Answer: 9079
Q622023 · 25 Jan 2023 · Shift 2
When the hydrogen ion concentration $[H^{+}]$ changes by a factor of 1000, the value of pH of the solution ____
1. A.decreases by 2 units
2. B.increases by 2 units
3. C.decreases by 3 units
4. D.increases by 1000 units
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Answer: C
Q642023 · 24 Jan 2023 · Shift 1
Assertion A : Hydrolysis of an alkyl chloride is a slow reaction but in the presence of $NaI$ , the rate of the hydrolysis increases. Reason R : $I^{-}$ is a good nucleophile as well as a good leaving group. In the light of the above statements, choose the correct answer from the options given below
1. A.A is true but R is false
2. B.A is false but R is true
3. C.Both A and R are true and R is the correct explanation of A
4. D.Both A and R are true but R is NOT the correct explanation of A
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Answer: C
Q692023 · 24 Jan 2023 · Shift 1
1. A.
2. B.
3. C.
4. D.
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Answer: A
Q872023 · 24 Jan 2023 · Shift 1· Numerical answer
The dissociation constant of acetic acid is $x \times 1 0^{- 5}$ . When $25 mL$ of $0.2 M C H_{3} COONa$ solution is mixed with $25 mL$ of $0.02 M C H_{3} COOH$ solution, the pH of the resultant solution is found to be equal to 5. The value of $x$ is ____
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Answer: 10
Q882023 · 24 Jan 2023 · Shift 1· Numerical answer
At $298 K$ , a 1 litre solution containing $10 mmol$ of $C r_{2} O_{7}^{2 -}$ and $100 mmol$ of $C r^{3 +}$ shows a pH of 3.0. Given : $C r_{2} O_{7}^{2 -} \to C r^{3 +}$ ; $E^{\circ} = 1.330V$ and $\frac{2.303 RT}{F} = 0.059 V$ The potential for the half cell reaction is $x \times 1 0^{- 3} V$ . The value of $x$ is ____
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Answer: 917
Q652023 · 24 Jan 2023 · Shift 2
1. A.
2. B.
3. C.
4. D.
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Answer: C
Q882023 · 24 Jan 2023 · Shift 2· Numerical answer
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Answer: 85