MCQs of Chemical Kinetics

Chemical Kinetics MCQs

MCQs of Chemical Kinetics

Showing 161 to 170 out of 228 Questions

161.

For a first order reaction, concentration of reactant decreases from 0.08 M to 0.04 M in 45 minutes.

t_{\frac{1}{2}}

= _____ .

(a)	108.4
(b)	45
(c)	22.5
(d)	90

162.

The half reaction time required to decrease initial concentration from 40% to 20% is 20minute. What time will be taken to decrease initial concentration from 10% to 5% ?

(a)	60 minute
(b)	5 minute
(c)	10 minute
(d)	20 minute

163.

If 2 hours are required for the decay of

\frac{3}{4}

of radioactive substance, what is its half life period ?

(a)	15 minutes
(b)	30 minutes
(c)	45 minutes
(d)	60 minutes

164.

For a first order reaction, initial concentration of reactant was decreased from 0.05 M to 0.015 M in 45 minutes. Calculate the half life period for this reaction.

(a)	87.42 minutes
(b)	25.90 minutes
(c)	78.72 minutes
(d)	77.20 minutes

165.

Which graph is required to get positive slope for first order reaction ?

(a)	$- \log_{10} [A] \to t$
(b)	$- \log_{e} [A] \to t$
(c)	$\log_{10} [A] \to \log t$
(d)	$[A] \to t$

166.

t_{\frac{1}{2}}

of a radioactive element is 560 days. What amount of radio active element will left behind after 550 days for 1 g.

(a)	$\frac{1}{2} g$
(b)	$\frac{1}{4} g$
(c)	$\frac{1}{8} g$
(d)	$\frac{1}{16} g$

167.

The concentration of first order reaction decreases to 50 mol/dm³ from 800 mol/dm³ in

2 \times 10^{4}

seconds, then what will be the rate constant of this reaction in sec^-1 ?

(a)	$2 \times 10^{4}$
(b)	$3.45 \times 10^{- 5}$
(c)	$1.386 \times 10^{- 4}$
(d)	$2 \times 10^{- 4}$

168.

Rate constant of a first order reaction is

2.303 \times 10^{- 2} \sec^{- 1}

. What time is required for concentration to become

\frac{1}{10}

part from its initial concentration ?

(a)	10 seconds
(b)	2303 seconds
(c)	100 seconds
(d)	230.3 seconds

169.

Total order of reaction

X + Y \to X Y

is 3. the order of reaction with respect to X is 2. State the differential rate equation for the reaction.

(a)	$- \frac{d [X]}{d t} = K {[X]}^{3} {[Y]}^{0}$
(b)	$- \frac{d [X]}{d t} = K {[X]}^{2} [Y]$
(c)	$- \frac{d [X]}{d t} = K {[X]}^{0} {[Y]}^{3}$
(d)	$- \frac{d [X]}{d t} = K [X] {[Y]}^{2}$

170.

For the reaction,

${CH}_{3} {COOCH}_{3} + H_{2} O \overset{H^{+}}{\to} {CH}_{3} COOH + {CH}_{3} OH$

which if the following statements is correct ?

(a)	If concentration of ester is doubled, the reaction rate becomes 4 times.
(b)	It is a pseudo first order reaction.
(c)	Its molecularity is one but order of reaction is two.
(d)	$Rate = K [Ester] [H_{2} O]$

Showing 161 to 170 out of 228 Questions