JEE Mains
2026
MCQ
Observe the following equilibrium in a 1 L flask.
A(g) ⇌ B(g)
At T(K), the equilibrium concentrations of A and B are 0.5 M and 0.375 M respectively. 0.1 moles of A is added into the flask and heated to T(K) to establish the equilibrium again. The new equilibrium concentrations (in M) of A and B are respectively
JEE Mains
2026
MCQ
Consider the following gaseous equilibrium in a closed container of volume ' $V$ ' at $\mathrm{T}(\mathrm{K})$.
$ \mathrm{P}_2(\mathrm{~g})+\mathrm{Q}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{PQ}(\mathrm{~g}) $
2 moles each of $\mathrm{P}_2(\mathrm{~g}), \mathrm{Q}_2(\mathrm{~g})$ and $\mathrm{PQ}(\mathrm{g})$ are present at equilibrium. Now one mole each of ' $\mathrm{P}_2$ ' and ' $\mathrm{Q}_2$ ' are added to the equilibrium keeping the temperature at $\mathrm{T}(\mathrm{K})$. The number of moles of $\mathrm{P}_2, \mathrm{Q}_2$ and PQ at the new equilibrium, respectively, are
JEE Mains
2026
MCQ
Consider the general reaction given below at 400 K
$ x \mathrm{~A}(\mathrm{~g}) \rightleftharpoons y \mathrm{~B}(\mathrm{~g}) . $
The values of $K_p$ and $K_c$ are studied under the same condition of temperature but variation in $x$ and $y$.
(i) $\mathrm{K}_{\mathrm{p}}=85.87$ and $\mathrm{K}_{\mathrm{c}}=2.586$ appropriate units
(ii) $\mathrm{K}_{\mathrm{p}}=0.862$ and $\mathrm{K}_{\mathrm{c}}=28.62$ appropriate units
The values of $x$ and $y$ in (i) and (ii) respectively are :
JEE Mains
2026
MCQ
Consider the following reactions in which all the reactants and products are present in gaseous state
$ \begin{aligned} & 2 x y \rightleftharpoons x_2+y_2 \,\,\mathrm{~K}_1=2.5 \times 10^5 \\ & x y+\frac{1}{2} z_2 \rightleftharpoons x y z \,\,\mathrm{~K}_2=5 \times 10^{-3} \end{aligned} $
The value of $\mathrm{K}_3$ for the equilibrium $\frac{1}{2} x_2+\frac{1}{2} y_2+\frac{1}{2} z_2 \rightleftharpoons x y z$ is :
JEE Mains
2026
MCQ
One mole each of He and $\mathrm{A}(\mathrm{g})$ are taken in a 10 L closed flask and heated to 400 K to establish the following equilibrium.
$ \mathrm{A}(\mathrm{~g}) \rightleftharpoons \mathrm{B}(\mathrm{~g}) $
$\mathrm{K}_{\mathrm{c}}$ for this reaction at 400 K is 4.0 . The partial pressures (in atm) of He and B(g) are respectively (at equilibrium)
(Assume $\mathrm{He}, \mathrm{A}(\mathrm{g})$ and $\mathrm{B}(\mathrm{g})$ behave as ideal gases)
(Given : $\mathrm{R}=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ )
JEE Mains
2026
MCQ
The reaction $\mathrm{A}(\mathrm{g}) \rightleftharpoons \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$ was initiated with the amount ' a ' of $\mathrm{A}(\mathrm{g})$. At equilibrium it is found that the amount of $\mathrm{A}(\mathrm{g})$ remaining is ( $\mathrm{a}-x$ ) at a total pressure of p .
The equilibrium constant Kp of the reaction can be calculated from the expression :
JEE Mains
2026
MCQ
At $\mathrm{T}(\mathrm{K})$, the equilibrium constant of
$\mathrm{A}_2(g)+\mathrm{B}_2(g) \rightleftharpoons \mathrm{C}(g)$ is $2.7 \times 10^{-5}$.
What is the equilibrium constant for
$\frac{1}{3} \mathrm{~A}_2(\mathrm{~g})+\frac{1}{3} \mathrm{~B}_2(\mathrm{~g}) \rightleftharpoons \frac{1}{3} \mathrm{C}(\mathrm{g})$ at the same temperature?
JEE Mains
2025
MCQ
In the following system, $\mathrm{PCl}_5(\mathrm{~g}) \leftrightharpoons \mathrm{PCl}_3(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g})$ at equilibrium, upon addition of xenon gas at constant T \& p , the concentration of
JEE Mains
2025
MCQ
Given below are two statements :
Statement I : A catalyst cannot alter the equilibrium constant $\left(\mathrm{K}_{\mathrm{c}}\right)$ of the reaction, temperature remaining constant.
Statement II : A homogenous catalyst can change the equilibrium composition of a system, temperature remaining constant.
In the light of the above statements, choose the correct answer from the options given below
JEE Mains
2025
MCQ
Consider the following chemical equilibrium of the gas phase reaction at a constant temperature : $\mathrm{A}(\mathrm{g}) \rightleftharpoons \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$
If $p$ being the total pressure, $K_p$ is the pressure equilibrium constant and $\alpha$ is the degree of dissociation, then which of the following is true at equilibrium?
JEE Mains
2025
MCQ
Consider the equilibrium
$ \mathrm{CO}(\mathrm{g})+3 \mathrm{H}_2(\mathrm{~g}) \rightleftharpoons \mathrm{CH}_4(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{~g}) $
If the pressure applied over the system increases by two fold at constant temperature then
(A) Concentration of reactants and products increases.
(B) Equilibrium will shift in forward direction.
(C) Equilibrium constant increases since concentration of products increases.
(D) Equilibrium constant remains unchanged as concentration of reactants and products remain same.
Choose the correct answer from the options given below :
JEE Mains
2025
MCQ
At temperature T, compound $AB_{2(g)}$ dissociates as $AB_{2(g)} \rightleftharpoons AB_{(g)} + \frac{1}{2} B_{2(g)}$ having degree of dissociation $ x $ (small compared to unity). The correct expression for $ x $ in terms of $ K_p $ and $ p $ is:
JEE Mains
2025
MCQ
For the reaction,
$\mathrm{H}_2(\mathrm{~g})+\mathrm{I}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{HI}(\mathrm{~g})$
Attainment of equilibrium is predicted correctly by :
JEE Mains
2025
MCQ
Consider the reaction
$\mathrm{X}_2 \mathrm{Y}(\mathrm{~g}) \rightleftharpoons \mathrm{X}_2(\mathrm{~g})+\frac{1}{2} \mathrm{Y}_2(\mathrm{~g})$
The equation representing correct relationship between the degree of dissociation (x) of $\mathrm{X}_2 \mathrm{Y}(\mathrm{g})$ with its equilibrium constant Kp is __________.
Assume $x$ to be very very small.
JEE Mains
2025
MCQ
A vessel at 1000 K contains $\mathrm{CO}_2$ with a pressure of 0.5 atm . Some of $\mathrm{CO}_2$ is converted into CO on addition of graphite. If total pressure at equilibrium is 0.8 atm , then Kp is :
JEE Mains
2024
MCQ
For the given hypothetical reactions, the equilibrium constants are as follows :
$\begin{aligned}
& \mathrm{X} \rightleftharpoons \mathrm{Y} ; \mathrm{K}_1=1.0 \\
& \mathrm{Y} \rightleftharpoons \mathrm{Z} ; \mathrm{K}_2=2.0 \\
& \mathrm{Z} \rightleftharpoons \mathrm{W} ; \mathrm{K}_3=4.0
\end{aligned}$
The equilibrium constant for the reaction $\mathrm{X} \rightleftharpoons \mathrm{W}$ is
JEE Mains
2024
MCQ
The ratio $\frac{K_P}{K_C}$ for the reaction :
$\mathrm{CO}_{(\mathrm{g})}+\frac{1}{2} \mathrm{O}_{2(\mathrm{~g})} \rightleftharpoons \mathrm{CO}_{2(\mathrm{~g})}$ is :
JEE Mains
2024
MCQ
At $-20^{\circ} \mathrm{C}$ and $1 \mathrm{~atm}$ pressure, a cylinder is filled with equal number of $\mathrm{H}_2, \mathrm{I}_2$ and $\mathrm{HI}$ molecules for the reaction
$\mathrm{H}_2(\mathrm{~g})+\mathrm{I}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{HI}(\mathrm{g})$, the $\mathrm{K}_{\mathrm{p}}$ for the process is $x \times 10^{-1}$.
$\mathrm{x}=$ __________.
[Given : $\mathrm{R}=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$]
JEE Mains
2024
MCQ
Given below are two statements :
Statement I : On passing $\mathrm{HCl}_{(\mathrm{g})}$ through a saturated solution of $\mathrm{BaCl}_2$, at room temperature white turbidity appears.
Statement II : When $\mathrm{HCl}$ gas is passed through a saturated solution of $\mathrm{NaCl}$, sodium chloride is precipitated due to common ion effect.
In the light of the above statements, choose the most appropriate answer from the options given below :
JEE Mains
2024
MCQ
The following reaction occurs in the Blast furnance where iron ore is reduced to iron metal
$\mathrm{Fe}_2 \mathrm{O}_{3(s)}+3 \mathrm{CO}_{(g)} \rightleftharpoons \mathrm{Fe}_{(\mathrm{l})}+3 \mathrm{CO}_{2(g)}$
Using the Le-chatelier's principle, predict which one of the following will not disturb the equilibrium.
JEE Mains
2024
MCQ
The equilibrium constant for the reaction
$\mathrm{SO}_3(\mathrm{~g}) \rightleftharpoons \mathrm{SO}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g})$
is $\mathrm{K}_{\mathrm{c}}=4.9 \times 10^{-2}$. The value of $\mathrm{K}_{\mathrm{c}}$ for the reaction given below is $2 \mathrm{SO}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{SO}_3(\mathrm{~g})$ is :
JEE Mains
2024
MCQ
$\mathrm{A}_{(\mathrm{g})} \rightleftharpoons \mathrm{B}_{(\mathrm{g})}+\frac{\mathrm{C}}{2}(\mathrm{g})$ The correct relationship between $\mathrm{K}_{\mathrm{P}}, \alpha$ and equilibrium pressure $\mathrm{P}$ is
JEE Mains
2024
MCQ
For the given reaction, choose the correct expression of $\mathrm{K}_{\mathrm{C}}$ from the following :-
$\mathrm{Fe}_{(\mathrm{aq})}^{3+}+\mathrm{SCN}_{(\mathrm{aq})}^{-} \rightleftharpoons(\mathrm{FeSCN})_{(\mathrm{aq})}^{2+}$
JEE Mains
2023
MCQ
For a concentrated solution of a weak electrolyte ($\mathrm{K}_{\text {eq }}=$ equilibrium constant) $\mathrm{A}_{2} \mathrm{B}_{3}$ of concentration '$c$', the degree of dissociation '$\alpha$' is :
JEE Mains
2023
MSQ
The effect of addition of helium gas to the following reaction in equilibrium state, is :
$\mathrm{PCl}_{5}(\mathrm{g}) \rightleftharpoons \mathrm{PCl}_{3}(\mathrm{g})+\mathrm{Cl}_{2}(\mathrm{g})$
JEE Mains
2022
MCQ
The equilibrium constant for the reversible reaction
2A(g) $\rightleftharpoons$ 2B(g) + C(g) is K1
${3 \over 2}$A(g) $\rightleftharpoons$ ${3 \over 2}$B(g) + ${3 \over 4}$C(g) is K2.
K1 and K2 are related as :
JEE Mains
2022
MCQ
4.0 moles of argon and 5.0 moles of PCl5 are introduced into an evacuated flask of 100 litre capacity at 610 K. The system is allowed to equilibrate. At equilibrium, the total pressure of mixture was found to be 6.0 atm. The Kp for the reaction is :
[Given : R = 0.082 L atm K$-$1 mol$-$1]
JEE Mains
2022
MCQ
For a reaction at equilibrium
A(g) $\rightleftharpoons$ B(g) + ${1 \over 2}$ C(g)
the relation between dissociation constant (K), degree of dissociation ($\alpha$) and equilibrium pressure (p) is given by :
JEE Mains
2020
MCQ
The value of KC is 64 at 800 K for the reaction
N2(g) + 3H2(g) ⇌ 2NH3(g)
The value of KC for the following reaction is :
NH3(g) ⇌ ${1 \over 2}$N2(g) + ${3 \over 2}$H2(g)
JEE Mains
2020
MCQ
For the reaction
Fe2N(s) + ${3 \over 2}$H2(g) ⇌ 2Fe(s) + NH3(g)
JEE Mains
2020
MCQ
The variation of equilibrium constant with
temperature is given below :
| Temperature |
Equilibrium Constant |
| T1 = 25oC |
K1 = 10 |
| T2 = 100oC |
K2 = 100 |
The values of $\Delta $H
o, $\Delta $G
o at
T
1 and $\Delta $G
o at T
2
(in kJ mol
–1) respectively, are close to :
[Use
R = 8.314 J K
–1 mol
–1]
JEE Mains
2020
MCQ
Consider the following reaction:
N2O4(g) ⇌ 2NO2(g); $\Delta $Ho = +58 kJ
For each of the following cases (a, b), the direction in which the equilibrium shifts is :
(a) Temperature is decreased.
(b) Pressure is increased by adding N2
at constant T.
JEE Mains
2020
MCQ
If the equilibrium constant for
A ⇌ B + C is $K_{eq}^{(1)}$ and that of
B + C ⇌ P is $K_{eq}^{(2)}$, the equilibrium
constant for A ⇌ P is :
JEE Mains
2020
MCQ
For the equilibrium A ⇌ B , the variation of the
rate of the forward (a) and reverse (b) reaction
with time is given by :
JEE Mains
2020
MCQ
An open beaker of water in equilibrium with
water vapour is in a sealed container. When a
few grams of glucose are added to the beaker
of water, the rate at which water molecules :
JEE Mains
2020
MCQ
In the figure shown below reactant A
(represented by square) is in equilibrium with
product B (represented by circle). The
equilibrium constant is :
JEE Mains
2019
MCQ
The INCORRECT match in the following is :
JEE Mains
2019
MCQ
In which one of the following equilibria, Kp $ \ne $ KC ?
JEE Mains
2019
MCQ
For the reaction,
2SO2(g) + O2(g) = 2SO3(g), $\Delta $H = –57.2 kJ mol–1
and KC = 1.7 × 1016
Which of the following statement is incorrect ?
JEE Mains
2019
MCQ
For the following reactions, equilibrium
constants are given :
S(s) + O2(g) ⇋ SO2(g); K1 = 1052
2S(s) + 3O2(g) ⇋ 2SO3(g); K2 = 10129
The equilibrium constant for the reaction,
2SO2(g) + O2(g) ⇋ 2SO3(g) is :
JEE Mains
2019
MCQ
Two solids dissociate as follows –
The total pressure when both the solids dissociated simultaneously is -
JEE Mains
2019
MCQ
In a chemical reaction,
the initial concentration of B was 1.5 times of the
concentration of A, but the equilibrium concentrations of A and B were found to be equal. The equilibrium constant (K) for the aforesaid chemical reaction is -
JEE Mains
2019
MCQ
Consider the reaction
N2(g) + 3H2(g) $\rightleftharpoons$ 2NH3(g)
The equilibrium constant of the above reaction is Kp. If pure ammonia is left to dissociate, the partial pressure of ammonia at equilibrium is given by (Assume that PNH3 << Ptotal at equilibrium)
JEE Mains
2019
MCQ
5.1 g NH4SH is introduced in 3.0 L evacuated flask at 327ºC. 30% of the solid NH4SH decomposed to NH3 and H2S as gases . The Kp of the reaction at 327oC is (R = 0.082 L atm mol–1 K–1, Molar mass of S = 32 g mol–1 molar mass of N = 14 g mol–1)
JEE Mains
2019
MCQ
The values of Kp/Kc for the following reactions at 300 K are, respectively : (At 300 K, RT = 24.62 dm3 atm mol–1)
N2(g) + O2(g) $\rightleftharpoons$ 2 NO(g)
N2O4(g) $\rightleftharpoons$ 2 NO(g)
N2(g) + 3H2(g) $\rightleftharpoons$ 2 NH3(g)
JEE Mains
2019
MCQ
Consider the following reversible chemical reactions :
The relation between K
1 and K
2 is :
JEE Mains
2018
MCQ
The gas phase reaction 2NO2(g) $ \to $ N2O4(g) is an exothermic reaction. The decomposition of N2O4, in equilibrium mixture of NO2(g) and N2O4(g), can be increased by :
JEE Mains
2018
MCQ
At a certain temperature in a $5$ $L$ vessel, 2 moles of carbon monoxide and 3 moles of chlorine were allowed to reach equilibrium according to the reaction,
CO + Cl2 $\rightleftharpoons$ COCl2
At equilibrium, if one mole of CO is present then equilibrium constant (Kc) for the reaction is :
JEE Mains
2018
MCQ
In which of the following reactions, an increase in the volume of the container will favour the formation of products?
JEE Mains
2017
MCQ
The following reaction occurs in the Blast Furnace where iron ore is reduced to iron
metal :
Fe2O3(s) + 3 CO(g) $\rightleftharpoons$ 2 Fe(1) + 3 CO2(g)
Using the Le Chatelier’s principle, predict which one of the following will not disturb the equilibrium ?
JEE Mains
2016
MCQ
A solid XY kept in an evacuated sealed container undergoes decomposition to form a mixture of gases X and Y at temperature T. The equilibrium pressure is 10 bar in this vessel. Kp for this reaction is :
JEE Mains
2016
MCQ
The equilibrium constant at 298 K for a reaction A + B $\leftrightharpoons$ C + D is 100. If the initial concentration of
all the four species were 1M each, then equilibrium concentration of D (in mol L–1) will be:
JEE Mains
2015
MCQ
The standard Gibbs energy change at 300 K for the reaction 2A $\leftrightharpoons$ B + C is 2494.2 J. At a given time,
the composition of the reaction mixture is [A] = 1/2, [B] = 2 and [C] = 1/2. The reaction proceeds in the: [R = 8.314 J/K/mol, e = 2.718]
JEE Mains
2014
MCQ
For the reaction SO2 (g) + ${1 \over 2} O_2(g) \leftrightharpoons$ SO3(g).
if KP = KC(RT)x where the symbols have usual meaning then
the value of x is: (assuming ideality)
JEE Mains
2012
MCQ
The equilibrium constant (KC) for the reaction N2(g) + O2(g) $\to$ 2NO(g) at temperature T is 4 $\times$ 10–4. The value of KC for the reaction, NO(g) $\to$ 1/2N2(g) + 1/2O2(g) at the same temperature is :
JEE Mains
2011
MCQ
A vessel at 1000 K contains CO2 with a pressure of 0.5 atm. Some of the CO2 is converted into CO on
the addition of graphite. If the total pressure at equilibrium is 0.8 atm, the value of K is :
JEE Mains
2010
MCQ
In aqueous solution the ionization constants for carbonic acid are
K1 = 4.2 x 10–7 and K2 = 4.8 x 10–11
Select the correct statement for a saturated 0.034 M solution of the carbonic acid.
JEE Mains
2008
MCQ
For the following three reactions a, b and c, equilibrium constants are given:
a. CO (g) + H2O (g) $\leftrightharpoons$ CO2(g) + H2 (g) ; K1
b. CH4 (g) + H2O (g) $\leftrightharpoons$ CO(g) + 3H2 (g) ; K2
c. CH4 (g) + 2H2O (g) $\leftrightharpoons$ CO2(g) + 4H2 (g) ; K3
JEE Mains
2008
MCQ
The equilibrium constants KP1 and KP2 for the reactions X $\leftrightharpoons$ 2Y and Z $\leftrightharpoons$ P + Q, respectively are in
the ratio of 1 : 9. If the degree of dissociation of X and Z be equal then the ratio of total pressure at
these equilibria is :
JEE Mains
2006
MCQ
The equilibrium constant for the reaction
SO3 (g) $\leftrightharpoons$ SO2 (g) + $1 \over 2$ O2 (g)
is Kc = 4.9 $\times$ 10–2. The value of Kc for the reaction
2SO2 (g) + O2 (g) $\leftrightharpoons$ 2SO3 (g) will be :
JEE Mains
2006
MCQ
Phosphorus pentachloride dissociates as follows, in a closed reaction vessel
PCl5 (g) $\leftrightharpoons$ PCl3 (g) + Cl2 (g)
If total pressure at equilibrium of the reaction mixture is P and degree of dissociation of PCl5 is x, the
partial pressure of PCl3 will be
JEE Mains
2005
MCQ
For the reaction
2NO2 (g) $\leftrightharpoons$ 2NO (g) + O2 (g), (Kc = 1.8 $\times$ 10-6 at 184oC) (R = 0.0831 kJ/(mol. K))
When Kp and Kc are compared at 184oC , it is found that :
JEE Mains
2005
MCQ
The exothermic formation of ClF3 is represented by the equation:
Cl2 (g) + 3F2 (g) $\leftrightharpoons$ 2ClF3 (g); $\Delta H$ = -329 kJ
Which of the following will increase the quantity of ClF3 in an equilibrium mixture of
Cl2, F2 and ClF3?
JEE Mains
2005
MCQ
An amount of solid NH4HS is placed in a flask already containing ammonia gas at a
certain temperature and 0.50 atm. Pressure. Ammonium hydrogen sulphide
decomposes to yield NH3 and H2S gases in the flask. When the decomposition
reaction reaches equilibrium, the total pressure in the flask rises to 0.84 atm. The
equilibrium constant for NH4HS decomposition at this temperature is :
JEE Mains
2004
MCQ
What is the equilibrium expression for the reaction
P4 (s) + 5O2 $\leftrightharpoons$ P4O10 (s)?
JEE Mains
2004
MCQ
The equilibrium constant for the reaction N2(g) + O2(g) $\leftrightharpoons$ 2NO(g) at temperature T is
4 $\times$ 10-4. The value of Kc for the reaction NO(g) $\leftrightharpoons$ $1 \over 2$N2 (g) + $1 \over 2$O2 (g) at the same temperature is :
JEE Mains
2004
MCQ
For the reaction, CO(g) + Cl2(g) $\leftrightharpoons$ COCl2(g) the ${{{K_p}} \over {{K_c}}}$ is equal to :
JEE Mains
2003
MCQ
For the reaction equilibrium
N2O4 (g) $\leftrightharpoons$ 2NO2 (g)
the concentrations of N2O4 and NO2 at equilibrium are 4.8 $\times$ 10-2 and 1.2 $\times$ 10-2 mol L-1 respectively. The value of Kc for the reaction is
JEE Mains
2003
MCQ
Consider the reaction equilibrium
2 SO2 (g) + O2 (g) $\leftrightharpoons$ 2 SO3 (g); $\Delta H^o$ = -198 kJ
One the basis of Le Chatelier's principle, the condition favourable for the forward reaction is :
JEE Mains
2002
MCQ
Change in volume of the system does not alter which of the following equilibria?
JEE Mains
2002
MCQ
For the reaction CO (g) + (1/2) O2 (g) $\leftrightharpoons$ CO2 (g), Kp/Kc is :