Chemical & Ionic Equilibrium · JEE Main previous year questions

The dissociation constant of acetic acid is $x\times 10^{-5}$. When $25\mathrm{mL}$ of $0.2\mathrm{M}\mathrm{C}{\mathrm{H}}_3\mathrm{COONa}$ solution is mixed with $25\mathrm{mL}$ of $0.02\mathrm{M}\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}$ solution, the pH of the resultant solution is found to be equal to 5. The value of $x$ is ____

At $298\mathrm{K}$, a 1 litre solution containing $10\mathrm{mmol}$ of $\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7^{2-}$ and $100\mathrm{mmol}$ of $\mathrm{C}{\mathrm{r}}^{3+}$ shows a pH of 3.0. Given : $\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7^{2-}\to \mathrm{C}{\mathrm{r}}^{3+}$ ; ${\mathrm{E}}^{\circ }=1.330V$ and $\frac{2.303\mathrm{RT}}{\mathrm{F}}=0.059\mathrm{V}$ The potential for the half cell reaction is $x\times 10^{-3}\mathrm{V}$. The value of $x$ is ____

1. A.
2. B.
3. C.
4. D.

1. A.
2. B.
3. C.
4. D.

If the solubility product of $\mathrm{PbS}$ is $8\times 10^{-28}$, then the solubility of $\mathrm{PbS}$ in pure water at $298\mathrm{K}$ is $\mathrm{x}\times 10^{-16}\mathrm{mol}{\mathrm{L}}^{-1}$. The value of $\mathrm{x}$ is __________. (Nearest Integer) [Given : $\sqrt{2}=1.41$]

Consider the reaction $4\mathrm{HN}{\mathrm{O}}_3(\mathrm{l})+3\mathrm{KCl}(\mathrm{s})\to \mathrm{C}{\mathrm{l}}_2(\mathrm{g})+\mathrm{NOCl}(\mathrm{g})+2{\mathrm{H}}_2\mathrm{O}(\mathrm{g})+3\mathrm{KN}{\mathrm{O}}_3(\mathrm{s})$ The amount of $\mathrm{HN}{\mathrm{O}}_3$ required to produce $110.0\mathrm{g}$ of $\mathrm{KN}{\mathrm{O}}_3$ is (Given: Atomic masses of H, O, N and K are 1, 16, 14 and 39, respectively.)

1. A.$32.2\mathrm{g}$
2. B.$69.4\mathrm{g}$
3. C.$91.5\mathrm{g}$
4. D.$162.5\mathrm{g}$

$200\mathrm{mL}$ of $0.01\mathrm{M}\mathrm{HCl}$ is mixed with $400\mathrm{mL}$ of $0.01\mathrm{M}{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$. The pH of the mixture is ____. Given: $\log 2=0.30,\log 3=0.48,\log 5=0.70,\log 7=0.84,\log 11=1.04$

1. A.$1.14$
2. B.$1.78$
3. C.$2.34$
4. D.$3.02$

A compound 'X' is a weak acid and it exhibits colour change at pH close to the equivalence point during neutralization of $\mathrm{NaOH}$ with $\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}$. Compound 'X' exists in ionized form in basic medium. The compound 'X' is

1. A.methyl orange
2. B.methyl red
3. C.phenolphthalein
4. D.erichrome Black T

The number of stereoisomers formed in a reaction of $(\pm )\mathrm{Ph}(\mathrm{C}=\mathrm{O})\mathrm{C}(\mathrm{OH})(\mathrm{CN})\mathrm{Ph}$ with $\mathrm{HCN}$ is ____. [where Ph is $-{\mathrm{C}}_6{\mathrm{H}}_5$]

${\text{K}}_{\text{a}}$ for butyric acid (${\text{C}}_3{\text{H}}_7\text{COOH}$) is $2\times 10^{-5}$. The pH of $0.2\text{ M}$ solution of butyric acid is _________ $\times 10^{-1}$. (Nearest integer) [Given $\log 2=0.30$]

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R Assertion A : Permanganate titrations are not performed in presence of hydrochloric acid. Reason R : Chlorine is formed as a consequence of oxidation of hydrochloric acid. In the light of the above statements, choose the correct answer from the options given below

1. A.Both A and R are true and R is the correct explanation of A
2. B.Both A and R are true but R is NOT the correct explanation of A
3. C.A is true but R is false
4. D.A is false but R is true

At $600\mathrm{K}$, $2\mathrm{mol}$ of $\mathrm{NO}$ are mixed with $1\mathrm{mol}$ of ${\mathrm{O}}_2$. $2{\mathrm{NO}}_{(\mathrm{g})}+{\mathrm{O}}_{2(\mathrm{g})}\rightleftarrows 2{\mathrm{NO}}_{2(\mathrm{g})}$ The reaction occurring as above comes to equilibrium under a total pressure of $1\mathrm{atm}$. Analysis of the system shows that $0.6\mathrm{mol}$ of oxygen are present at equilibrium. The equilibrium constant for the reaction is ____. (Nearest integer)

$2\mathrm{NO}+2{\mathrm{H}}_2\to {\mathrm{N}}_2+2{\mathrm{H}}_2\mathrm{O}$ The above reaction has been studied at $800^{\circ }\mathrm{C}$. The related data are given in the table below | Reaction serial number | Initial Pressure of $H_2/kPa$ | Initial Pressure of $NO/kPa$ | Initial rate $\left(\frac{-dp}{dt}\right)/(kPa/s)$ | | :--- | :--- | :--- | :--- | | 1 | 65.6 | 40.0 | 0.135 | | 2 | 65.6 | 20.1 | 0.033 | | 3 | 38.6 | 65.6 | 0.214 | | 4 | 19.2 | 65.6 | 0.106 | The order of the reaction with respect to NO is _________.

At $310\text{ K}$, the solubility of ${\mathrm{CaF}}_2$ in water is $2.34\times 10^{-3}\text{ g}/100\text{ mL}$. The solubility product of ${\mathrm{CaF}}_2$ is _________ $\times 10^{-8}(\text{mol}/\text{L}{)}^3$. (Given molar mass : ${\mathrm{CaF}}_2=78{\text{ g mol}}^{-1}$)

In the titration of ${\mathrm{KMnO}}_4$ and oxalic acid in acidic medium, the change in oxidation number of carbon at the end point is _________.

1. A.
2. B.
3. C.
4. D.

The number of molecule(s) or ion(s) from the following having non-planar structure is ____. $\mathrm{N}{\mathrm{O}}_3^{-},{\mathrm{H}}_2{\mathrm{O}}_2,\mathrm{B}{\mathrm{F}}_3,\mathrm{PC}{\mathrm{l}}_3,\mathrm{Xe}{\mathrm{F}}_4,\mathrm{S}{\mathrm{F}}_4,\mathrm{Xe}{\mathrm{O}}_3,\mathrm{P}{\mathrm{H}}_4^{+},\mathrm{S}{\mathrm{O}}_3,[\mathrm{Al}(\mathrm{OH}{)}_4{]}^{-}$

The dark purple colour of $\mathrm{KMn}{\mathrm{O}}_4$ disappears in the titration with oxalic acid in acidic medium. The overall change in the oxidation number of manganese in the reaction is :

1. A.$5$
2. B.$1$
3. C.$7$
4. D.$2$

1. A.
2. B.
3. C.
4. D.

At $298\mathrm{K}$, the equilibrium constant is $2\times 10^{15}$ for the reaction : $$\mathrm{Cu}(\mathrm{s})+2\mathrm{A}{\mathrm{g}}^{+}(\mathrm{aq})\rightleftharpoons \mathrm{C}{\mathrm{u}}^{2+}(\mathrm{aq})+2\mathrm{Ag}(\mathrm{s})$$ The equilibrium constant for the reaction $$\frac{1}{2}\mathrm{C}{\mathrm{u}}^{2+}(\mathrm{aq})+\mathrm{Ag}(\mathrm{s})\rightleftharpoons \frac{1}{2}\mathrm{Cu}(\mathrm{s})+\mathrm{A}{\mathrm{g}}^{+}(\mathrm{aq})$$ is $x\times 10^{-8}$. The value of $x$ is ____. (Nearest Integer)

In base vs. acid titration, at the end point methyl orange is present as

1. A.quinonoid form
2. B.heterocyclic form
3. C.phenolic form
4. D.benzenoid form

The equilibrium constant for the reversible reaction $2\text{A(g)}\rightleftharpoons 2\text{B(g)}+\text{C(g)}$ is $K_1$ $\frac{3}{2}\text{A(g)}\rightleftharpoons \frac{3}{2}\text{B(g)}+\frac{3}{4}\text{C(g)}$ is $K_2$. $K_1$ and $K_2$ are related as :

1. A.$K_1=\sqrt{K_2}$
2. B.$K_2=\sqrt{K_1}$
3. C.$K_2=K_1^{3/4}$
4. D.$K_1=K_2^{3/4}$

In which of the following half cells, electrochemical reaction is pH dependent?

1. A.$Pt\mid F{e}^{3+},F{e}^{2+}$
2. B.$Mn{O}_4^{-}\mid M{n}^{2+}$
3. C.$Ag\mid AgCl\mid C{l}^{-1}$
4. D.$\frac{1}{2}{F}_2\mid F^{-}$

1. A.
2. B.
3. C.
4. D.