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NEET Chemistry MCQ
Chemical Kinetics Mcq Neet Chemistry
Quiz 5
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Q.1
Half-life of a first order reaction is 10 min. What % of reaction will be completed in 100 min?
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a) 25%
0%
b) 50%
0%
c) 80%
0%
d) 99.9%
Explanation
Thus reaction completed = 100-0.1=99.9% Answer : (d)
Q.2
The rate constant for the reaction N2O5(g) → 2NO2(g) + ½ O2(g) is 2.3×10-2 sec-Which equation given below describes the change of [N2O5] with time [N2O5]0 and [N2O5]t? ... [ AIIMS 2004 ]
0%
a) [N2O5]0 = [N2O5]tekt
0%
b) [N2O5]t = [N2O5]0 + kt
0%
c) log10[N2O5]t = log10[N2O5]0 - kt
0%
d)
Explanation
Answer : (d)
Q.3
3A → B + C It would be a zero order reaction when ...[ CBSE 2002]
0%
a) the rate of reaction is proportional to square of concentration of A
0%
b) the rate of reaction remains same at any concentration of A
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c) the rate remains unchanged at any concentration of B and C
0%
d) the rate of reaction doubles if concentration of B is increased to double
Explanation
For zero order reaction rate = k thus independent of concentration Answer : (b)
Q.4
A substance reacts with initial concentration of a mol dm-3, according to zero order kinetics. the time it takes for the completion of reaction is : (k=rate constant, r0 initial concentration) [KCET 2006]
0%
a) k/R0
0%
b) R0/2k
0%
c) R0/k
0%
d) kR0
Explanation
For zero order rewaction R = kt For complition of reaction R = R0 ∴ t= R0/k Answer : (c)
Q.5
The rate of reaction depends upon .... [ BHU 2000]
0%
a) molar concentration
0%
b) atomic mass
0%
c) equivalent mass
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d) none of these
Explanation
Answer : (a)
Q.6
At 500K, the half-life period of a gaseous reaction at an initial pressure of 80 kPa is 350 sec. When the pressure is 40 kPa, the half-life period is 175 sec; the order of the reaction is
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a) zero
0%
b) one
0%
c) two
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d) two and half
Explanation
half life and order of reaction is given by Answer : (a)
Q.7
For the reaction 2A+B → 3C + D, which of the following does not express the reaction rate ...[ CBSE 2006]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
C is product thus must be positive Answer : (a)
Q.8
The rate constant for the hydrolysis reaction of an ester by dilute acid is 0.6931×10-3 s-The time required to change the concentration of eter from 0.04M to 0.01M is
0%
a) 6931 sec
0%
b) 1000 sec
0%
c) 4000 sec
0%
d) 2000 sec
Explanation
Answer : (d)
Q.9
he rate of reaction between A and B increases by a factor of 100, when the concentration of A is increased 10 folds. The order of reaction with respect to A is ...
0%
a) 2
0%
b) 1
0%
c) zero
0%
d) 10
Explanation
Answer : (a)
Q.10
The decay constant of 6C14 is 2.31 ×10-4 year-Its half-life is ...[ BHU 2000]
0%
a) 2×103 yrs
0%
b) 2.5×103 yrs
0%
c) 3×103 yrs
0%
d) 3.5×103 yrs
Explanation
Decay of nucleus is first order reaction use formula Answer : (c)
Q.11
The activation energy of exothermic reaction A → B is 80kJmol-The heat of reaction is 200kJmol-The activation energy for the reaction B →A (in kJ/mol) will be
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a) 40
0%
b) 80
0%
c) 200
0%
d) 280
Explanation
ΔH = Ed - Eb -200 = 80 - Eb Eb = 280 kJ/mol Answer : (d)
Q.12
Activation energy of the reaction is ...
0%
a) the energy released during the reaction
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b) the energy evolved when activated complex is formed
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c) minimum amount of energy needed to overcome the potential barrier
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d) the energy needed to form one mole of the product
Explanation
Answer : (c)
Q.13
In the first order reaction, the concentration of reaction is reduced to 25% in one hour. The half life period of the reaction is ...[ AFMC 2005]
0%
a) 1/4 hr
0%
b) 1/2 hr
0%
c) 2 hrs
0%
d) 4 hrs
Explanation
1st half-period = 50% 2nd half period = 25% Thus two half period = 1 hr ∴ half period = 1/2 hr Answer : (b)
Q.14
For the reaction 2N2O5 → 4NO2 + O2 rate and rate constant are 1.02×10-4 Ms-1 and 3.4×10-5 s-1 respectively then concentration of N2O5 at that time will be ...[ CBSE 2001]
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a) 17.732 M
0%
b) 3 M
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c) 1.02 ×10-4 M
0%
d) 3.4 ×105 M
Explanation
Rate = k[N2O5] 1.02×10-4 = 3.4 ×10-[N2O5] 1.02×10-4 = 3.4×10-5 [N2O5] [N2O5]=3M Answer : (b)
Q.15
The half-life period of a first order reaction is 1 min 40 seconds. Calculate its rate constant.
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a) 6.93 × 10-3 min-1
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b) 6.93 × 10-3 sec-1
0%
c) 1.93× 10-3 sec
0%
d) 1.93× 103 sec
Explanation
For first order reaction half-life Answer : (b)
Q.16
ssertion k= Ae-Ea/RT, the Arrhenius equation represents the dependence of rate constant with temperature Reason Plot of log K against 1/T is linear and the activation energy can be calculated with this plot
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a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion
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b) The Assertion and Reason are true but Reason is not correct explanation of Assertion
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c) Assertion is true but, Reason is false
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d) Assertion is false but, Reason is true
Explanation
Answer : (a)
Q.17
For a chemical reaction A → B, the rate of reaction doubles when the concentration of A is increased four times. The order of reaction for A is ...[ BHU 1995]
0%
a) zero
0%
b) half
0%
c) one
0%
d) two
Explanation
Answer : (b)
Q.18
For the reaction N2O5(g) → 2NO2(g) + ½O2(g), the value of rate of disappearance of N2O5 is given as 6.25×10-3 mol L-1s-The rate of formation of NO2 and O2 is given retrospectively as ...[ CBSE 2010]
0%
a) 6.25×10-3 mol L-1s-1 and 6.25×10-3 mol L-1s-1
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b) 1.25×10-2 mol L-1s-1 and 3.125×10-3 mol L-1s-1
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c) 6.25×10-3 mol L-1s-1 and 3.125×10-3 mol L-1s-1
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d) 1.25×10-2 mol L-1s-1 and 6.25×10-3 mol L-1s-1
Explanation
Answer : (b)
Q.19
Assertion Order can be different from molecularity of a reaction Reason Slow step is the rate determining step and may involve lesser number of reactants
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a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion
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b) The Assertion and Reason are true but Reason is not correct explanation of Assertion
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c) Assertion is true but, Reason is false
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d) Assertion is false but, Reason is true
Explanation
Answer : (b)
Q.20
3A → 2B, rate of reaction is equals to ...[ CBSE 2002]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer : (b)
Q.21
The activation energy for a simple chemical reaction A → B is Ea, in forward direction. The activation energy for reverse reaction ...[ CBSE 2003]
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a) can be less than or more than Ea
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b) if always double of Ea
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c) is negative of Ea
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d) is always less than Ea
Explanation
Ea be the activation energy in forward direction E'a be the activation energy in reverse direction Now heat of reaction is given br ΔH ΔH = (Ea -E'a) E'a = Ea + ΔH When ΔH = -ve , E'a > Ea or for exothermic reaction When ΔH = +ve , E'a < Ea or for endothermic reaction since it is not specified reaction is endo or exo thermic option "a" is correct Answer : (a)
Q.22
The rate of a chemical reaction
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a) increases as the reaction proceeds
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b) decreases as the reaction proceeds
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c) may increases or decreases during the reaction
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d) remains constant as the reaction proceeds
Explanation
Answer : (b)
Q.23
In a first order reaction A → P, the ratio of R0/R was found to be 8 after 60 minutes. If concentration is 0.1M, then the rate of reaction in moles of A reacted per minute is ...[ AIIMS 1996]
0%
a) 2.226×10-3 mol litre-1 min-1
0%
b) 3.466×10-3 mol litre-1 min-1
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c) 4.455×10-3 mol litre-1 min-1
0%
d) 5.532×10-3 mol litre-1 min-1
Explanation
Answer : (b)
Q.24
The specific rate constant of a first order reaction depends on ...[ AFMC 2001]
0%
a) time
0%
b) temperature
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c) concentration of product
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d) concentration of the reactants
Explanation
Answer : (b)
Q.25
If a first order reaction takes 32 minutes for 80% completion, then time required for 50% completion is ...[ AMU 2006]
0%
a) 1.386 min
0%
b) 13.86 min
0%
c) 8 min
0%
d) 4 min
Explanation
If Ro=100, then R=100 - 80 = 20 Time for 50% completion = 0.693/0.05 = 13.86 min Answer : (b)
Q.26
For which of the following, the units of rate and rate constant of the reaction are identical?
0%
a) zero order
0%
b) first order
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c) second order
0%
d) third order
Explanation
Answer : (a)
Q.27
According to the collision theory of reation rates, the rate of reaction increases with temperature due to
0%
a) decrease in the activation energy
0%
b) greater number of collisions
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c) higher velocity of reacting ,molecules
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d) greater number of molecules having the activation energy
Explanation
Answer : (d)
Q.28
Activation energy (Ea) and rate constant (k1 and k2) of a chemical reaction at two different temperatures (T1 and T2) are related by ...[ AIPMT 2012]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer : (d)
Q.29
A substance undergoes first order decomposition. The decomposition follows two parallel first order reactions as, k1 = 1.26×10-4 sec-1, k2 = 3.8 ×10-5 sec-1 The percentage distribution of B and C are ...[ Kerala PMT 2004]
0%
a) 75% B and 25% C
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b) 80% B and 20% C
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c) 60% B nad 40% C
0%
d) 90% and 10% C
Explanation
Given reaction is parallel reaction ∴ %[C]= 100 - 76.83 = 23.17% Answer : (a)
Q.30
Rate of reaction for following reaction is 3×10-3 mol litre-1 min-What is the value of -d[B]/dt A(g) +3B(g) → 2C(g)
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a) 3×10-3
0%
b) 9×10-3
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c) 10-3
0%
d) 1.5×10-3
Explanation
Answer : (b)
0 h : 0 m : 1 s
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