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14 multiple-choice questions related to chemical equilibrium, including equations and calculations. The questions cover topics such as equilibrium constants, reaction quotients, and active mass. The questions are suitable for advanced high school or undergraduate students studying chemistry.
Typology: Exercises
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1. One mole of SO 3 was placed in a litre reaction vessel at a
certain temperature. The following equilibrium was established
2 SO 3 ⇌ 2 SO (^) 2 O 2
At equilibrium 0.6 moles of (^) SO 2 were formed. The
equilibrium constant of the reaction will be [MP PMT 1991]
(a) 0.36 (b) 0.
(c) 0.54 (d) 0.
2. For the following homogeneous gas reaction 4 NH (^) 3 5 O 2 ⇌
4 NO 6 H 2 O^ ,^ the^ equilibrium^ constant^ Kc has^ the
dimension of [CPMT 1990; MP PET/PMT 1998]
(a)
10 Conc (b)
1 Conc
(c)
1 Conc (d) It is dimensionless
3. Consider the imaginary equilibrium
The equilibrium constant Kc has the unit [RPMT 2000]
(a) Mole^2 litre -^2 (b) Litre mole-^1
(c) Mole litre -^1 (d) Litre^2 mole-^2
4. For the reaction CO ( g ) 2 H 2 ( g ) ⇌ CH 3 OH ( g ), true
condition is
(a) K (^) p Kc (b) K (^) p Kc
(c) K (^) p Kc (d) (^) Kc 0 but Kp 0
5. For the reaction () 2
1 CO ( g ) O 2 g ⇌ CO 2 ( g ); c
p
K
K is
equivalent to [MP PET/PMT 1998; AIEEE 2002]
(a) 1 (b) RT
(c) RT
(d) ( RT )^1 /^2
( )
2 ( )
2 ( )
g g g
N O NO O what is the ratio of the rate of
decomposition of N 2 O 5 to rate of formation of NO 2
[DCE 2003]
(a) 1 : 2 (b) 2 : 1
(c) 1 : 4 (d) 4 : 1
7. The reaction quotient ( Q ) for the reaction
N 2 ( g ) 3 H 2 ( g ) ⇌ 2 NH 3 ( g )
is given by 3 2 2
2 3 [ ][ ]
Q . The reaction will proceed from
right to left is [CBSE PMT 2003]
(a) Q = 0 (b) Q = Kc
(c) Q < Kc (d) Q > Kc
Where Kc is the equilibrium constant
8. In the thermal dissociation of PCl 5 , the partial pressure in the
gaseous equilibrium mixture is 1.0 atmosphere when half of
PCl 5 is found to dissociate. The equilibrium constant of the
reaction ( Kp )in atmosphere is [JIPMER 2002]
(a) 0.25 (b) 0.
(c) 1.00 (d) 0.
9. HI was heated in a closed tube at C
o 440 till equilibrium is
obtained. At this temperature 22% of (^) HI was dissociated. The
equilibrium constant for this dissociation will be
[MP PET 1988, 92; MNR 1987; UPSEAT 2000]
(a) 0.282 (b) 0.
(c) 0.0199 (d) 1.
10. The following equilibrium exists in aqueous solution
CH 3 COOH ⇌ CH COO ^ H
without a change in temperature, then the [MNR 1987]
(a) Concentration of
CH (^) 3 COO will increase
(b) Concentration of
CH (^) 3 COO will decrease
(c) Equilibrium constant will increase
(d) Equilibrium constant will decrease
11. Which of the following is not favourable for SO 3 formation
2 SO (^) 2 ( g ) O 2 ( g ) ⇌ 2 SO (^) 3 ( g ); H 45. 0 kcal
[IIT 1984; MP PET 1997]
(a) High pressure
(b) High temperature
(c) Decreasing SO 3 concentration
(d) Increasing reactant concentration
12. 120 gm of urea are present in 5 litre solution, the active mass
of urea is [MP PMT 1994]
(a) 0.2 (b) 0.
(c) 0.4 (d) 0.
13. For the system 2 A ( g ) B ( g )⇌ 3 C ( g ), the expression for
equilibrium constant K is [NCERT 1973; DCE 1999]
(a) [ 3 ]
(b) 3
2
(c) [ 2 ] []
(d) [] []
2
3
14. If concentration of reactants is increased by ' x ', then K becomes [AFMC 1997]
(a) ln ( K / x ) (b) K / x
(c) K x (d) K
1. (d) ( 10. 6 )
( 0. 3 )
2 ( 0. 6 )
3
2
2 (^2)
Kc.
2. (b) K has the units of (^) (conc. ) n , where n 10 9 1 3. (c) Unit of (^) Kc (unit of concentration)n
= ( mole litre –^1 )n
n = 10 – 9 = 1
Kc mol Litre –^1.
4. (c) When nr np then K (^) p Kc
where nr = no. of moles of reactant
np = no. of moles of product.
5. (c) For 2 2
2
111 ( )
K (^) p KcRT^2
1
( )
KcRT^ ; K RT
c
p^1
6. (b) 2 N 2 O 5 HNO 2 O 2
Rate of decomposition of N 2 O 5
dt
K [ NO ] . 2
(^1 )
Rate of formation of dt
dNO NO
[ ] . 4
(^1 ) 2
Ratio = 2 : 1
7. (d) If Q Kc reaction will proceed right to left to decrease
concentration of product.
8. (d) PCl 5 ⇌ PCl 3 (^) Cl 2
Initial conc. 1 0 0
At equilibrium 0.5 0.5 0.
1
75
5 0. 5
[ 1 ( 0. 5 )]
1 0. 5 0. 5
( 1 )
2 2
2
x
Px Kp
9. (c) 2 HI ⇌ H 2 (^) I 2
Initial conc. 2 moles 0 0
at equilibrium 2 100
2 2
2 2
10. (b) When adding HCl in CH 3 COOH solution the
concentration of H is increased. So reaction is proceed
in reverse direction and the concentration of
CH (^) 3 COO
is decreased.
11. (b) The reaction is exothermic so high temperature will favour backward reaction. 12. (c) Active mass litre
moles
in
wt.in /molecularwt. V litre
gm
13. (d) [ ][]
2
3
14. (d) There is no effect of change in concentration on equilibrium constant.