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NEET Chemistry MCQ
Chemical And Ionic Equilibrium Mcq
Quiz 4
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Q.1
The equilibrium N2 + O2 ↔ 2NO is established in reaction vessel of 2.5L capacity. the amount of N2 and O2 taken at the start were respectively 2 moles and 4moles. Half a mole of nitrogen has been used up at equilibrium. the molar concentration of nitric oxide is [ KCET 1985]
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a) 0.2
0%
b) 0.4
0%
c)0.6
0%
d)0.1
Explanation
At equilibrium number of moles are N2=1.5 NO=1 molThus molar concentration=1/2.5=0.4Answer: (b)
Q.2
In case of gaseous homogenous reaction, the active mass of the reactant is obtained by the expression ..[Tamil nadu CET 2002]
0%
a) PV/RT
0%
b) P/RT
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c)RT/P
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d)nRT/V
Explanation
From ideal gas equation PV=nRTP/RT=n/V=concentration Answer:(b)
Q.3
For the reaction 2A + B ↔ C, ΔH=+x cals, which one of the following conditions would favour the yield of C on the basis of Le Chatelier principle? [ Harayana CEET 1991]
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a) Higher pressure, higher temperature
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b) Only low temperature
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c)Higher pressure, low temperature
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d)only low pressure
Explanation
In the reaction Δng > 1, reaction is endothermic . Hence high pressure and high temperature will favour forward reaction Answer:(a)
Q.4
At a certain temperature, the following reactions: NO(g) + ½O2(g) ↔ NO2() NO2(g) + NO(g) ↔ N2O3 (g) have equilibrium constant K1 and K2 respectively. The equilibrium constant for the reaction2NO(g) + ½O2(g) ↔ N2O3(g) at the same temperature would be ..[Pb CET sample paper 1993]
0%
a) K1 + K2
0%
b) K1 / K2
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c) K2 / K1
0%
d) K1 K2
Explanation
If the equation is written in number of steps, then its equilibrium constant will be the multiple of the equilibrium constant of each step Answer: (d)
Q.5
The effect of increasing the pressure on the following equilibrium 2A + 3B ↔ 3 A + 2B is ...[EAMCET 1980]
0%
a)Forward reaction is favoured
0%
b) Backward reaction is favoured
0%
c)No effect
0%
d)None of above
Explanation
Number of gas molecules on both side same, thus no effect Answer: (c)
Q.6
In which of the following cases, does the reaction go farthest to completion? [ MLNR 1990]
0%
a) K=102
0%
b) K=10
0%
c)K=10-2
0%
d)K=1
Explanation
Greater the value of K, more it goes towards completionAnswer: (a)
Q.7
For the system A(g) + 2B(g) ↔ C(g), the equilibrium concentrations are A=0.06 mol/L, B=0.12 mol/L, C=0.216 mol/L The Keq for the reaction is ..[CPMT 1983]
0%
a) 250
0%
b) 416
0%
c)4 × 10-3
0%
d)125
Explanation
Answer:(a)
Q.8
A chemical system is in equilibrium. Addition of catalyst would result in [ KCET 1993]
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a) increase in the rate of forward reaction
0%
b) increase in the rate of reverse reaction
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c) a new reaction path
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d) increase the amount of heat evolved in the reaction
Explanation
Answer: (c)
Q.9
The equilibrium constant in a reversible chemical reaction at a given temperature .. [ AIIMS 1982]
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a)depends on the initial concentration of the reactants
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b) depends on the concentration of one of the products at equilibrium
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c)does not depend on the initial concentration of reactants
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d)is not characteristics of the reaction
Explanation
Answer: (c)
Q.10
56g of N2 and 6g of H2 were kept at 400°C in 1 litre vessel. The equilibrium mixture contained 27.54g of NHthe approximate value for Ke for the above reaction in mol2/L is ...[CBSE PMT 1989]
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a) 10
0%
b) 20
0%
c)30
0%
d)40
Explanation
56g of N2=2 moles6g of H2=3 moles27.54 g of NH3=1.62 molesAt equilibrium number of moles are N2=1.19 molesH2=0.57 molesNH3=1.62 molesAnswer: (a)
Q.11
A and B are gaseous substances which react reversibly to give two gaseous substances C and D, accompanied by the liberation of heat. When the reaction reaches equilibrium, it is observed that Kp=Kc. the equilibrium can not be disturbed by [ KCET 1988]
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a) Adding A
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b) Adding D
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c)Increasing pressure
0%
d)Rising temperature
Explanation
As Δng=0Change in pressure will not disturb equilibrium constant Answer:(c)
Q.12
In the gas phase reactionC2H4 + H2 ↔ C2H6the equilibrium constant can be expressed in units of ..[CBSE PMT 1992]
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a) litre-1 mol-1
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b) mol2 litre-2
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c) litre mole-1
0%
d) mole litre-1
Explanation
Answer: (c)
Q.13
Pure ammonia is placed in vessel at temperature where its dissociation is appreciable. At equilibrium ..[IIT 1984]
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a)Kp does not change significantly with pressure
0%
b) α does not change with pressure
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c)concentration of NH3 does not change with pressure
0%
d)concentration of H2 is less than that of N2
Explanation
Answer: (a)
Q.14
Two moles of HI were heated in a sealed tube at 440°C till the equilibrium was reached. HI was found to be 22% decomposed. the equilibrium constant for dissociation is [ AFMC 1994]
0%
a) 0.282
0%
b) 0.0796
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c)0.0199
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d)1.99
Explanation
At equilibrium number of moles areHI=2 -0.44=1.6 aH2=0.22 I2=0.22 Answer: (c)
Q.15
For reaction at equilibrium, Le Chatelier's principle predicts the effects of ..[Bihar CEE 1992]
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a) temperature and pressure
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b) temperature and volume
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c)pressure and volume
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d)only volume
Explanation
Answer:(a)
Q.16
K1 and K2 are equilibrium constant for reaction (1) and (2)N2(g) + O2(g) ↔ 2NO(g) ...(1)NO(g) ↔ ½ N2(g) + ½O2(g) ..(2)Then .. [CBSE PMT 1989]
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a) K1=(1/K2)2
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b) K1=K22
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c) K1K2=1
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d) K1=(K2)0
Explanation
Answer: (a)
Q.17
k1 and k2 are the velocity constant of forward and backward reaction. The equilibrium constant K of the reaction is ..[KCET 1985]
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a)k1 × k2
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b) k1 - k2
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c)k1/k2
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d)none of above
Explanation
Answer: (c)
Q.18
According to Le-Chatelier's principle, adding heat to a solid and liquid in equilibrium will cause the [ MLNR 1990]
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a) temperature to increase
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b) temperature to decrease
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c)amount of liquid to decrease
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d)amount of solid to decrease
Explanation
Answer: (d)
Q.19
The decomposition of N2O4 to NO2 is carried out at 280°C in chloroform. When equilibrium is reached 0.2 mol of N2O4 and 2×10-3 mol of nO2are present in 2 litre solution. The equilibrium constant for the reaction N2O4 ↔ 2NO2 is ..[AIIMS 1984]
0%
a) 1 ×10-3
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b) 2 ×10-3
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c)1 ×10-5
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d)2 ×10-5
Explanation
Answer:(c)
Q.20
A cylinder filled with a movable piston contains liquid water in equilibrium with water vapour at 25°C. Which one of the following operations results in a decrease in the equilibrium vapour pressure? [ AIIMS 1993]
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a) Moving the piston downward a short distance
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b) removing a small amount of vapour
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c) removing a small amount of the liquid water
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d) Dissolving salt in water
Explanation
By dissolving salt in water vapour pressure of water decreases Answer: (d)
Q.21
CH3COOH + C2H5OH ↔ CH3COOC2H5 + H2O In the above reaction one mole each of the acetic acid and alcohol are heated in the presence of little conc.H2SOOn equilibrium being attained [ CPMT 1985]
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a)1 mole of ethyl acetate is formed
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b) 2 moles of ethyl acetate are formed
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c)1/3 mole of ethyl acetate is formed
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d)unpredictable
Explanation
Equilibrium constant is not given.Answer: (d)
Q.22
The active mass of 64g of HI in a two litre flask would be ..[CPMT 1979]
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a) 2
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b) 1
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c)5
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d)0.25
Explanation
Mol.mass of HI=1+127=12864g of hI=64/128=0.5 mole[HI]=0.5/2 M=0.25MAnswer: (d)
Q.23
In an exothermic reaction, a 10° rise in temperature will [ Bangalore PMT 1993]
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a) decrease the value of equilibrium constant
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b) double the value of Kc
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c)not produce any change in Kc
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d)produce some increase in Kc
Explanation
Answer:(a)
Q.24
For the homogeneous reaction4NH3 + 5O2 ↔ 4NO + 6H2 the equilibrium constant Kc has the units of ..[CPMT 1990]
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a) conc.+10
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b) conc.+1
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c) conc.-1
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d) It is dimension less
Explanation
Answer: (b)
Q.25
Equilibrium constant for the reaction 2NO(g) + Cl2(g) ↔ 2NOCl(g) is correctly given by the expression.. [ CPMT 1983]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
By the law of chemical equilibriumAnswer: (b)
Q.26
A reaction reaches a state of chemical equilibrium only when ..[Pb CET 1989]
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a) the reactants and the products are reacting
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b) the concentrations of the reactants and the products become equal
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c)the products reacts together at the same rate at which they are formed
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d)all the reactants and the products are in the same state of matter
Explanation
equilibrium is achieve when rate of formed and rate of reverse direction reaction is sameAnswer: (c)
Q.27
in a chemical reaction, the rate constant for the backward reaction is 7.5×10-4 and the equilibrium constant is 1.the rate constant for forward reaction is ..[KCET 1989]
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a) 5 ×10-4
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b)2 ×10-3
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c) 1.125 ×10-3
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d) 9 ×10-4
Explanation
Answer:(c)
Q.28
Which one of the following information can be obtained on the basis of Le Chatelier principle? [ CBSE PMT 1992]
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a) Dissociation constant of weak acid
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b) Entropy change in a reaction
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c) Equilibrium constant of a chemical reaction
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d) Shift in equilibrium position on changing value of a constraint
Explanation
Answer: (d)
Q.29
The equilibrium constant , K for the reaction 2HI(g) ↔ H2(g) + I2(g) at room temperature is 2.85 and that at 698K, it is 1.4×10-This implies that : [ NCERT 1984]
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a)HI is exothermic compound
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b) HI is very stable at room temperature
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c)HI is relatively less stable than H2 and I2
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d)HI is resonance stabiles
Explanation
Decrease in K with increase in temperature indicates reaction is exothermic if forward direction . AS reaction is exothermic , HI is less stable than H2 and I2Answer: (c)
Q.30
At 500K, the equilibrium constant for reaction cisC2H2Cl2 ↔ transC2H2Cl2 is 0.6At the same temperature, the equilibrium constant for the reactiontransC2H2Cl2 ↔ cisC2H2Cl2
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a) 0.66
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b) 1.67
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cg)0.76
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d)2.6
Explanation
For reverse reaction K'=1/K K'=1/0.66=1.67Answer: (b)
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