Question Set B

Tamilnadu 12th Standard Chemistry Chemical Kinetics Important Questions Study Material - QB365

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Questions:

Multiple Choice Question

50 x 1 = 50

If the initial concentration of the reactant is doubled, the time for half reaction is also doubled. Then the order of the reaction is______.

(a)

Zero

(b)

one

(c)

Fraction

(d)

none

The rate constant of a reaction is 5.8 x 10^-2 S^-1 The order of the reaction is ______.

(a)

First order

(b)

zero order

(c)

Second order

(d)

Third order

For a first order reaction, the rate constant is 6.909 min^-1the time taken for 75% conversion in minutes is _______.

(a)

\(\left( \frac { 3 }{ 2 } \right) { \log 2 }\)

(b)

\(\left( \frac { 2 }{ 3 } \right) \log2\)

(c)

\(\left( \frac { 3 }{ 2 } \right) \log\left( \frac { 3 }{ 4 } \right) \)

(d)

\(\left( \frac { 2 }{ 3 } \right) \log\left( \frac { 4 }{ 3 } \right) \)

In a reversible reaction, the enthalpy change and the activation energy in the forward direction are respectively −x kJ mol^-1 and y kJ mol^-1. Therefore, the energy of activation in the backward direction is _______.

(a)

(y-x) kJ mol^-1

(b)

(x+y) J mol^-1

(c)

(x-y) KJ mol^-1

(d)

(x+y) x 10³J mol^-1

For a reaction Rate = k[acetone]^3/2 then unit of rate constant and rate of reaction respectively is _______.

(a)

(mol L^-1 S^-1),(mol^1/2L^1/2S^-1)

(b)

(mol^-1/2L^1/2s^-1),(mol L^-1s^-1)

(c)

(mol^1/2L^1/2s^-1),(mol L^-1s^-1)

(d)

(mol L s^-1),(mol^1/2L^1/2s)

The cation leaves its normal position in the crystal and moves to some interstitial position, the defect in the crystal is known as _____.

(a)

Schottky defect

(b)

F center

(c)

Frenkel defect

(d)

non-stoichiometric defect

If ‘a’ stands for the edge length of the cubic system sc, bcc, and fcc. Then the ratio of radii of spheres in these systems will be respectively ________.

(a)

\(\left( \frac { 1 }{ 2 } a;\frac { \sqrt { 3 } }{ 2 } a;\frac { \sqrt { 2 } }{ 2 } a \right) \)

(b)

\(\left( \sqrt { 1a } :\sqrt { 3a } :\sqrt { 2a } \right) \)

(c)

\(\left( \frac { 1 }{ 2 } a:\frac { \sqrt { 3 } }{ 4 } a:\frac { 1 }{ 2\sqrt { 2 } } a \right) \)

(d)

\(\frac { 1 }{ 2 } a:\sqrt { 3 } a:\frac { 1 }{ \sqrt { 2 } } a\)

The fraction of total volume occupied by the atoms in a simple cubic is ________.

(a)

\(\left( \frac { \pi }{ 4\sqrt { 2 } } \right) \)

(b)

\(\left( \frac { \pi }{ 6 } \right) \)

(c)

\(\left( \frac { \pi }{ 4 } \right) \)

(d)

\(\left( \frac { \pi }{ 3\sqrt { 2 } } \right) \)

A solid compound XY has NaCl structure if the radius of the cation is 100pm, the radius of the anion will be ________.

(a)

\(\left( \frac { 100 }{ 0.414 } \right) \)

(b)

\(\left( \frac { 0.732 }{ 100 } \right) \)

(c)

100 x 0.414

(d)

\(\left( \frac { 0.414 }{ 100 } \right) \)

10.

For a first order reaction A ⟶ product with initial concentration x mol L^-1, has a half life period of 2.5 hours. For the same reaction with initial concentration \(\left( \frac { x }{ 2 } \right) \) mol L^-1 the half life is

(a)

(2.5 x 2) hours

(b)

\(\left( \frac { 2.5 }{ 2 } \right) \) hours

(c)

2.5 hours

(d)

Without knowing the rate constant, t_1/2 cannot be determined from the given data

11.

For a first order reaction A ⟶ B the rate constant is x min⁻¹. If the initial concentration of A is 0.01M, the concentration of A after one hour is given by the expression.

(a)

001. e^−x

(b)

1 x 10^-2(1-e^-60x)

(c)

(1 x 10^-2)e^-60x

(d)

none of these

12.

In a solid atom M occupies ccp lattice and \(\left( \frac { 1 }{ 3 } \right) \) of tetrahedral voids are occupied by atom N. Find the formula of solid formed by M and N ________.

(a)

(b)

M₃N

(c)

MN₃

(d)

M₃N₂

13.

Fac-mer isomerism is shown by _______.

(a)

[CO(en)₃]³⁺

(b)

[Co(NH₃)₄(Cl)₂]⁺

(c)

[Co(NH₃)₃(Cl)₃]

(d)

[Co(NH₃)₅Cl]SO₄

14.

Formula of tris(ethane-1, 2-diamine)iron(II)phosphate _______.

(a)

[Fe(CH₃-CH(NH₂)₂)₃](PO₄)₃

(b)

[Fe(H₂N-CH₂-CH₂-NH₂)₃](PO₄)

(c)

[Fe(H₂N-CH₂-CH₂-NH₂)₃](PO₄)₂

(d)

[Fe(H₂N-CH₂-CH₂-NH₂)₃]₃(PO₄)₂

15.

Which one of the following complexes is not expected to exhibit isomerism?

(a)

[Ni(NH₃)₄(H₂O)₂]²⁺

(b)

[Pt(NH₃)₂Cl₂]

(c)

[Co(NH₃)₅SO₄]Cl

(d)

[FeCl₆]^3-

16.

How many geometrical isomers are possible for [Pt(Py)(NH₃)(Br)(Cl)]?

(a)

(b)

(c)

(d)

17.

Which one of the following will give a pair of enantiomorphs?

(a)

[Cr(NH₃)₆][Co(CN)₆]

(b)

[Co(en)₂Cl₂]Cl

(c)

[Pt(NH₃)₄][PtCl₄]

(d)

[Co(NH₃)₄Cl₂]NO₂

18.

Crystal field stabilization energy for high spin d⁵ octahedral complex is _______.

(a)

-0.6\({ \Delta }_{ 0 }\)

(b)

(c)

2(P-\({ \Delta }_{ 0 }\))

(d)

2(P+\({ \Delta }_{ 0 }\))

19.

IUPAC name of the complex K₃[Al(C₂O₄)₃] is _______.

(a)

potassium trioxalatoaluminium (III)

(b)

possium trioxalatoaluminate (II)

(c)

potassium trisoxalatoaluminate (III)

(d)

potassium trioxalatoaluminate (III)

20.

Oxidation state of Iron and the charge on the ligand NO in [Fe(H₂O)₅NO]SO₄ are_______.

(a)

+2 and 0 respectively

(b)

+3 and 0 respectively

(c)

+3 and -1 respectively

(d)

+1 and +1 respectively

21.

The sum of primary valence and secondary valence of the metal M in the complex [M(en)₂(Ox)]Cl is________.

(a)

(b)

(c)

-3

(d)

22.

Which one of the following is not correct?

(a)

La(OH)₃ is less basic than Lu(OH)₃

(b)

In lanthanoid series ionic radius of Ln³⁺ ions decreases

(c)

La is actually an element of transition metal series rather than lanthanide series

(d)

Atomic radii of Zr and Hf are same because of lanthanide contract

23.

Which of the following oxidation states is most common among the lanthanoids?

(a)

(b)

(c)

(d)

24.

How many moles of I₂ are liberated when 1 mole of potassium dichromate react with potassium iodide?

(a)

(b)

(c)

(d)

25.

The correct order of increasing oxidizing power in the series _______.

(a)

VO₂⁺ < Cr₂O₇^2- < MnO₄^-

(b)

Cr₂O₇^2- < VO₂⁺ < MnO₄^-

(c)

Cr₂O₇^2- < MnO₄^- < VO₂⁺

(d)

MnO₄^- < Cr₂O₇^2- < VO₂⁺

26.

The catalytic behaviour of transition metals and their compounds is ascribed mainly due to _______.

(a)

their magnetic behaviour

(b)

their unfilled d orbitals

(c)

their ability to adopt variable oxidation states

(d)

their chemical reactivity

27.

Which one of the following ions has the same number of unpaired electrons as present in V³⁺?

(a)

Ti³⁺

(b)

Fe³⁺

(c)

Ni²⁺

(d)

Cr³⁺

28.

Sc (Z = 21) is a transition element but Zinc (z = 30) is not because _______.

(a)

both Sc³⁺ and Zn²⁺ ions are colourless and form white compounds

(b)

In case of Sc, 3d orbital are partially filled but in Zn these are completely filled

(c)

last electron as assumed to be added to 4s level in case of zinc

(d)

both Sc and Zn do not exhibit variable oxidation states

29.

Duralumin is an alloy of ______.

(a)

Cu, Mn

(b)

Cu, Al, Mg

(c)

Al, Mn

(d)

Al, Cu, Mn, Mg

30.

Which of the following statements is not correct?

(a)

Beryl is a cyclic silicate

(b)

Mg₂SiO₄ is an orthosilicate

(c)

SiO₄⁴⁻is the basic structural unit of silicates

(d)

Feldspar is not aluminosilicate

31.

Which of the following is not sp² hybridised?

(a)

Graphite

(b)

graphene

(c)

Fullerene

(d)

dry ice

32.

Which of the following is strongest acid among all?

(a)

(b)

(c)

HBr

(d)

HCl

33.

Which one of the following compounds is not formed?

(a)

XeOF₄

(b)

XeO₃

(c)

XeF₂

(d)

NeF₂

34.

The basicity of pyrophosphorous acid ( H₄P₂O₅) is _______.

(a)

(b)

(c)

(d)

35.

On hydrolysis, PCl₃ gives________.

(a)

H₃PO₃

(b)

PH₃

(c)

H₃PO₄

(d)

POCl₃

36.

An element belongs to group 15 and 3^rdperiod of the periodic table, its electronic configuration would be_______.

(a)

1s² 2s² 2p⁴

(b)

1s² 2s² 2p³

(c)

1s² 2s² 2p⁶ 3s² 3p²

(d)

1s² 2s² 2p⁶ 3s² 3p³

37.

In which of the following, NH₃ is not used?

(a)

Nessler's reagent

(b)

Reagent for the analysis of IV group basic radical

(c)

Reagent for the analysis of III group basic radical

(d)

Tollen's reagent

38.

The basic structural unit of silicates is _______.

(a)

\(\left( SiO_{ 3 } \right) ^{ 2- }\)

(b)

\(\left( SiO_{ 4 } \right) ^{ 2- }\)

(c)

\(\left( Sio \right) ^{ - }\)

(d)

\(\left( SiO_{ 4 } \right) ^{ 4- }\)

39.

Carbon atoms in fullerene with formula C₆₀have _______hybridisation.

(a)

sp³ hybridised

(b)

sp hybridised

(c)

sp² hybridised

(d)

partially sp² and partially sp³ hybridised

40.

Which of the following metals has the largest abundance in the earth’s crust?

(a)

Aluminium

(b)

Calcium

(c)

Magnesium

(d)

Sodium

41.

Boric acid is an acid because its molecule________.

(a)

contains replaceable H⁺ ion

(b)

gives up a proton

(c)

combines with proton to form water molecule

(d)

accepts OH^- from water, releasing proton.

42.

In the electrolytic refining of copper, which one of the following is used as anode?

(a)

Pure copper

(b)

Impure copper

(c)

Carbon rod

(d)

Platinum electrode

43.

Considering Ellingham diagram, which of the following metals can be used to reduce alumina?

(a)

(b)

(c)

(d)

44.

Which one of the following ores is best concentrated by froth – floatation method?

(a)

Magnetite

(b)

Haematite

(c)

Galena

(d)

Cassiterite

45.

Electrochemical process is used to extract_______.

(a)

Iron

(b)

Lead

(c)

Sodium

(d)

silver

46.

Wolframite ore is separated from tinstone by the process of________.

(a)

Smelting

(b)

Calcination

(c)

Roasting

(d)

Electromagnetic separation

47.

Match items in column - I with the items of column – II and assign the correct code.

Column-I		Column-II
A.	Cyanide process	(i)	Ultrapure Ge
B	Froth floatation process	(ii)	Dressing of ZnS
C	Electrolytic reduction	(iii)	Extraction of Al
D	Zone refining	(iv)	Extraction of Au
		(v)	Purification of Ni

(a)

A	B	C	D
(i)	(ii)	(iii)	(iv)

(b)

A	B	C	D
(iii)	(iv)	(v)	(i)

(c)

A	B	C	D
(iv)	(ii)	(iii)	(i)

(d)

A	B	C	D
(ii)	(iii)	(i)	(v)

48.

Which of the metal is extracted by Hall-Heroult process?

(a)

(b)

(c)

(d)

49.

Which one of the following reaction represents calcinations?

(a)

\(2Zn+{ O }_{ 2 }\rightarrow 2ZnO\)

(b)

\(2ZnS+3O_{ 2 }\rightarrow 2ZnO+2SO_{ 2 }\)

(c)

\(MgCO_{ 3 }\rightarrow MgO+CO_{ 2 }\)

(d)

Both (a) and (c)

50.

Bauxite has the composition ______.

(a)

Al₂O₃

(b)

Al₂O₃.nH₂O

(c)

Fe₂O₃.2H₂O

(d)

None of these

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Answers Key:

Multiple Choice Question

50 x 1 = 50

t_1/2 α \(\frac{1}{[A_{0}]^{n-1}}\)...(1)
If [A₀ = 2[A₀]; then t_1/2 = 2t_1/2
2t_1/2 α \(\frac{1}{[2A_{0}]^{n-1}}\)...(2)
(2)/(1) = \(2= \frac{1}{[2A_{0}]^{n-1}} \times \frac{1}{[A_{0}]^{n-1}}\)
\(2= \frac {[2A_{0}]^{n-1}} {[A_{0}]^{n-1}}\)
\(2= \frac {1} {2}^{n-1}\)
2 = (2^-1)^n-1
2¹ = (2^-n+1)
n = 0

(a)
First order

\(k=\frac { 2.303 }{ t } \log\frac { \left[ { A }_{ 0 } \right] }{ \left[ A \right] } \)
[A₀] = 100: [A] = 25
\(6.909=\frac { 2.303 }{ t } \log\frac { \left[ {100 } \right] }{ \left[ 25\right] } \)
\(t =\frac { 2.303 }{ 6.909 } \log(4)\)
\(t =\frac { 1 }{ 3 } \log(2^2)\)
\(= \left( \frac { 2 }{ 3 } \right) \log2\)

Rate = k[A]ⁿ
Rate = \(\frac{-\mathrm{d}[\mathrm{A}]}{\mathrm{dt}}\)
unit of rate = \(\frac{mol L^{-1}}{s}\)=mol L^-1/s^-1
unit of rate constant
\(=\frac{ (mol{ L }^{ -1 }{ S }^{ -1 }) }{ ({ mol }{ L }^{ -1 })^n } \)
= mol^1-nL^n-1s^-1
in the case
rate = k [Acetone]^3/2
n = 3/2
= mol^1-(3/2)L^(3/2)-1s^-1
(mol^-(1/2)L^(1/2)s^-1).

sc ⇒ 2r = a
⇒ r = a/2
bcc ⇒ 4r = \( \sqrt{3a} \) ⇒ r = \(\frac { \sqrt{3a}} {4}\)
fcc ⇒ 4r ⇒ \( \sqrt{2a} \) ⇒ r = \(\frac { \sqrt{2a}} {4} = \frac { a} {2\sqrt{2a}}\)
\(\left( \frac { a }{ 2 } :\frac { \sqrt { 3 } }{ 4 } a:\frac { a }{ 2\sqrt { 2 } } \right) \)

(b)
\(\left( \frac { \pi }{ 6 } \right) \)

For a fcc structure = r_x+ / r_y- = 0.414
Given that r_x⁺ = 100 pm
r_y = 100pm/0.414

10.

For a first order reaction
t_1/2 = \(\frac { 0.693 }{ { k }}\)
t_1/2 does not depend on the initial concentration and it remains constant (whatever may be the initial concentration)
t_1/2 = 2.5 hrs

11.

\(k=\frac { 2.303 }{ t } log\frac { \left[ { A }_{ 0 } \right] }{ \left[ A \right] } \)
\(k=\frac { 1 }{ t } ln \frac { \left[ { A }_{ 0 } \right] }{ \left[ A \right] } \)
\(e^{kt}=\frac { \left[ { A }_{ 0 } \right] }{ \left[ A \right] }\)
[A] = [A₀] e^kt
In this case
k = x min^-1 and [A₀] = 0.01 M = 1 x 10^-2M
t = 1 hour = 60 min
[A] = (1 x 10^-2)e^-60x

12.

If the total number of M atoms is n, then the number of tetrahedral voids = 2n
Given that \(\left( \frac { 1 }{ 3 } \right) ^{rd}\) of tetrahedral voids are occupied.
i.,e \(\left( \frac { 1 }{ 3 } \right) \times 2n\) are occupied by N atoms
\(\therefore\)M : N = n : \(\left( \frac { 2 }{ 3 } \right) n\)
= 1 : \(\frac { 2 }{ 3 }\)
Hence M₃N₂ = 3 : 2

13.

14.

[Fe(H₂N-CH₂-CH₂-NH₂)₃]₃(PO₄)₂
[Fe(en)₃]²⁺(\(PO_{4}^{3-}\))

15.

Option (a) and (b) -geometrical isomerism is possible
Option (c) - ionization isomerism is possible
Option (d) - no possibility to show either constitutional isomerism or stereo isomerism

16.

Three isomers. If we consider any one of the ligands as reference (say Py), the arrangement of other three ligands (NH₃, Br^- and Cl^-) with respect to (Py) gives three geometrical isomers.

17.

Complexes given in other options (a), (c) and (d) have symmetry elements and hence they are optically inactive.

18.

The electronic configuration t_2g³, e²_g
[ 3 x (-0.4)+ 2(0.6)]Δ₀
[-1.2 + 1.2] Δ₀ = 0

19.

(d)
potassium trioxalatoaluminate (III)

20.

[\( \overset{+}{Fe}\)(H₂O)₅\( \overset{+}{NO}\)]²⁺ SO^2-₄
+1 and +1 respectively

21.

In the complex [M(en)₂(Ox)]Cl For the central metal ion M3+
The primary valence is = +3
The secondary valence = 6
sum of primary valence and secondary valence = 3 + 6 = 9

22.