12th Standard Chemistry One Mark important Questions Book back and Creative - 2020

Download Tamil Nadu 12th Standard Chemistry question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.

Questions:

Multiple Choice Question

58 x 1 = 58

Sandmeyer's reaction occurs in the presence of _________ and __________

(a)

cuprous halide and halo acid

(b)

cupric halide and halogen

(c)

copper - zinc couple and H₂

(d)

none of these

A 1% solution of phenol is a _______

(a)

antiseptic

(b)

disinfectant

(c)

antimalarial drug

(d)

anthithistamine

The formulation of dettol contains ______________.

(a)

chloroxylenol

(b)

terpineol

(c)

alcohol

(d)

all of these

Which of the following cannot be prepared by Sandmeyer's reaction?

(a)

Iodobenzene

(b)

Fluorobenzene

(c)

both Iodobenzene and Fluorobenzene

(d)

neither Iodobenzene and Fluorobenzene

On hydrolysis, which one of the following disaccharide will give a ketose and an aldose?

(a)

Maltose

(b)

Sucrose

(c)

Lactose

(d)

All the above

Carbohydrates are

(a)

polyhydroxy aldehydes

(b)

polyhydroxy ketones

(c)

polyhydroxy acids

(d)

both (a) and (b)

The emf of the unknown half cell is _______.

(a)

E_measured = E_R - E_L

(b)

E_measured = E_L - E_R

(c)

E_measured = - nFE

(d)

E_measured = E^o - \(\frac{RT}{F}\) log

Standard electrode potential of Sn⁴⁺/ Sn²⁺ couple is +0.15 V and that of Cr³⁺ / Cr is 0.85 V. When connected, the cell potential will be ______.

(a)

1.10 V

(b)

1.00 V

(c)

0.70 V

(d)

0.30 V

Formic acid contains both __________ and ________ groups.

(a)

-CHO and OH

(b)

-CHO and X-O

(c)

-CHO and COOH

(d)

-CHO and -O-

10.

CH₃CH₂CH₂CH₂COOH and \({ CH }_{ 3 }-\overset { \underset { | }{ { CH }_{ 3 } } }{ CH } -{ CH }_{ 2 }COOH\) are examples of ________ isomerism.

(a)

geometrical

(b)

funcational

(c)

chain

(d)

postional

11.

The platinum catalyst used in the oxidation of SO₂ by contact process is poisoned by _______.

(a)

As₂O₃

(b)

V₂O₅

(c)

Fe₂O₃

(d)

CuCl₂

12.

The common name for 4-hydroxy toluene is ________.

(a)

p-cresol

(b)

m-cresol

(c)

resoricinol

(d)

catechol

13.

Degree if dissociation is nearly equal to for _______.

(a)

Strong acids and strong bases

(b)

Strong acids and weak bases

(c)

Weak acids and strong bases

(d)

Weak acids and weak bases

14.

Pick out the incorrect statement regarding Lewis acids and bases

(a)

A Lewis acid is a electron deficient molecule

(b)

Lewis bases is one which donates an electron pair

(c)

Lewis base is a cation

(d)

Lewis acid is a electron deficient molecule and Lewis base is a cation

15.

Which of the following gives violet colour with neutral ferric chloride solution?

(a)

phenol

(b)

glycerine

(c)

benzyl alcohol

(d)

ethanol

16.

The autocatalyst in the oxidation of oxalic acid by acidified KMnO₄ is _______.

(a)

K₂SO₄

(b)

MnSO₄

(c)

KMnO₄

(d)

CO₂

17.

Which of the following is a co-polymer?

(a)

Orlon

(b)

PVC

(c)

Teflon

(d)

PHBV

18.

Which of the following is an analgesic?

(a)

Streptomycin

(b)

Chloromycetin

(c)

Asprin

(d)

Penicillin

19.

Which of the following statement is correct?

(a)

Ovalbumin is a simple food reserve in egg-white

(b)

Blood proteins thrombin and fibrinogen are involved in blood clotting

(c)

Denaturation makes protein more active

(d)

Insulin maintains the sugar level of in the human body

20.

The number of sp² and sp³ hybridised carbon in fructose are respectively ______.

(a)

1 and 4

(b)

4 and 2

(c)

5 and 1

(d)

1 and 5

21.

Secondary nitro alkanes react with nitrous acid to form _______.

(a)

red solution

(b)

blue solution

(c)

green solution

(d)

yellow solution

22.

Nitrobenzene on reaction with Con HNO₃ / H₂SO₄ at 80-100^oC forms which one of the following products?

(a)

1,4 – dinitrobenzene

(b)

2,4,6 – tirnitrobenzene

(c)

1,2 – dinitrobenzene

(d)

1,3 – dinitrobenzene

23.

The IUPAC name of

(a)

but – 3- enoicacid

(b)

but – 1- ene-4-oic acid

(c)

but – 2- ene-1-oic acid

(d)

but -3-ene-1-oicacid

24.

Predict the product Z in the following series of reactions Ethanoic acid \(\overset { { PCI }_{ 5 } }{ \longrightarrow } X\overset { { C }_{ 6 }{ H }_{ 6 } }{ \underset { Anhydrous \ AlCI }-_{3}{ \longrightarrow } } Y\overset { 1){ CH }_{ 3 }MgBr }{ \underset { II){ H }_{ 3 }{ O }^{ + } }{ \longrightarrow } } Z.\)

(a)

(CH₃)₂ C(OH)C₆H₅

(b)

CH₃CH(OH)C₆H₅

(c)

CH₃CH(OH)CH₂- CH₃

(d)

25.

The reactions
is an example of ______.

(a)

Wurtz reaction

(b)

cyclic reaction

(c)

Williamson reaction

(d)

Kolbe reactions

26.

In the reaction Ethanol \(\overset { { PCl }_{ 5 } }{ \longrightarrow } X\overset { alc.KOH }{ \longrightarrow } Y\overset { { H }_{ 2 }{ SO }_{ 4 }/{ H }_{ 2 }O }{ \underset { 298k }{ \longrightarrow } } Z.\) The ‘Z’ is ______.

(a)

ethane

(b)

ethoxyethane

(c)

ethylbisulphite

(d)

ethanol

27.

If x is the amount of adsorb ate and m is the amount of adsorbent, which of the following relations is not related to adsorption process?

(a)

x/m = f(P) at constant T

(b)

x/m = f(T) at constant P

(c)

P = f(T) at constant x/m

(d)

x/m = PT

28.

Conductivity of a saturated solution of a sparingly soluble salt AB (1:1 electrolyte) at 298K is 1.85 ×10⁻⁵ S m⁻¹. Solubility product of the salt AB at 298K (Λ^o_m)_AB = 14 ×10⁻³S m² mol⁻¹.

(a)

5.7 x 10^-12

(b)

1.32 x 10⁻¹²

(c)

7.5 x 10⁻¹²

(d)

1.74 x 10^-12

29.

The equivalent conductance of M/36 solution of a weak monobasic acid is 6 mho cm² equivalent^-1 and at infinite dilution is 400 mho cm² equivalent^-1. The dissociation constant of this acid is ______.

(a)

1.25 x 10⁻⁶

(b)

6.25 x 10^-6

(c)

1.25 x 10⁻⁴

(d)

6.25 x 10 ^-5

30.

Which of the following relation is correct for degree of hydrolysis of ammonium acetate?

(a)

\(h=\sqrt { \frac { { K }_{ h } }{ C } } \)

(b)

\(h=\sqrt { \frac { { K }_{ a } }{ K_b } } \)

(c)

\(h=\sqrt { \frac { { K }_{ w } }{ { K }_{ a }.{ K }_{ b } } } \)

(d)

\(h=\sqrt { \frac { { { K }_{ a }.{ K }_{ b } } }{ { K }_{ w } } } \)

31.

Which will make basic buffer?

(a)

50 mL of 0.1M NaOH+25mL of 0.1M CH₃COOH

(b)

100 mL of 0.1M CH₃COOH+100 mL of 0.1M NH₄OH

(c)

100 mL of 0.1M HCl+200 mL of 0.1M NH₄OH

(d)

100 mL of 0.1M HCl+100 mL of 0.1M NaOH

32.

CH₃COOCH₃ + H₂O \(\overset { { H }^{ + } }{ \longrightarrow } \) CH₃COOH + CH₃OH is an example of _______ order reaction.

(a)

first

(b)

zero

(c)

third

(d)

pseudo

33.

What would be the rate of disappearance of oxygen, if the rate of formation of nitric oxide (NO) is 3.6 x 10^-3mol L^-1 s^-1?

(a)

4 x 10^-3mol L^-1s^-1

(b)

4 x 10^-3mol^-1 L^-1s^-1

(c)

4.5 x 10^-3mol L^-1s^-1

(d)

4.5 x 10^-3mol^-1 L^-1s^-1

34.

The high reactivity of fluorine is due to________.

(a)

high ionisation energy

(b)

low bond dissociation energy

(c)

low electron affinity

(d)

high electro negativity

35.

Which of the following is correct?

(a)

H₃PO₃ is dibasic and reducing

(b)

H₃PO₃ is dibasic and non-reducing

(c)

H₃PO₄ is tribasic and reducing

(d)

H₃PO₃ is tribasic and non-reducing

36.

Amorphous solids can also be called _______.

(a)

pseudo solids

(b)

true solids

(c)

super cooled liquids

(d)

both (a) & (c)

37.

Which of the following is incorrect statement about the Bragg's equation nλ = 2d sin θ?

(a)

n, represents order of reflection

(b)

λ, represents wave length of uv-rays used

(c)

θ, represents angle of incidence

(d)

d, represents distance between two parallel planes

38.

The silicates which contain discrete tetrahedral units are _______.

(a)

ortho silicates

(b)

sheet silicates

(c)

pyrosilicates

(d)

three dimensional silicates

39.

Group 14 elements have general electronic configuration _______.

(a)

ns²

(b)

ns²np⁴

(c)

ns²np⁶

(d)

ns²np²

40.

The element corresponding to the electronic configuration [Rn]5f³ 6d¹7s²is _________

(a)

Neptunium

(b)

Plutonium

(c)

Uranium

(d)

Americium

41.

Hybridisation of chromium ions and dichromate ions is ________.

(a)

Sp²

(b)

Sp³d

(c)

both (a) and (b)

(d)

None of these

42.

\(HgS_{ (s) }+{ O }_{ 2(g) }\longrightarrow { Hg }_{ (l) }+{ SO }_{ 2 }\uparrow \) The above reaction is an example of _________reduction.

(a)

metal

(b)

hydrogen

(c)

carbon

(d)

auto

43.

The process of heating of copper pyrites to remove sulphur is called ________.

(a)

froth flotation

(b)

roasting

(c)

calcination

(d)

smelling

44.

Magnu's green salt in________.

(a)

[Pt(NH₃)₄[[PtCl₄]

(b)

K[PtCl₃(C₂H₄)]

(c)

[Ni(CO)₄]

(d)

[Fe(Co)₅]

45.

The oxidation number of nickel in complex ion, [NiCI₄]^2- is _______.

(a)

(b)

-1

(c)

(d)

-2

46.

The correct difference between first and second order reactions is that________.

(a)

A first order reaction can be catalysed; a second order reaction cannot be catalysed.

(b)

The half life of a first order reaction does not depend on [A₀]; the half life of a second order reaction does depend on [A₀].

(c)

The rate of a first order reaction does not depend on reactant concentrations; the rate of a second order reaction does depend on reactant concentrations.

(d)

The rate of a first order reaction does depend on reactant concentrations; the rate of a second order reaction does not depend on reactant concentrations.

47.

In a first order reaction x ⟶ y; if k is the rate constant and the initial concentration of the reactant x is 0.1M, then, the half life is_____.

(a)

\(\left( \frac { \log2 }{ k } \right) \)

(b)

\(\left( \frac { 0.693 }{ (0.1)k } \right) \)

(c)

\(\left( \frac { In2 }{ k } \right) \)

(d)

none of these

48.

The number of unit cells in 8 gm of an element X (atomic mass 40) which crystallizes in bcc pattern is (N_A is the Avogadro number)________.

(a)

6.023 x 10²³

(b)

6.023 x 10²²

(c)

60.23 x 10²³

(d)

\(\left( \frac { 6.023\times { 10 }^{ 23 } }{ 8\times 40 } \right) \)

49.

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

50.

In which of the following coordination entities the magnitude of Δ₀ will be maximum?

(a)

[Co(CN)₆]^3-

(b)

[Co(C₂O₄)₃]^3-

(c)

[Co(H₂O)₆]³⁺

(d)

[Co(NH₃)₆]³⁺

51.

The most common oxidation state of actinoids is _______.

(a)

(b)

(c)

(d)

52.

Among the transition metals of 3d series, the one that has highest negative \(\left( \frac { M^{ 2+ } }{ M } \right) \) standard electrode potential is _______.

(a)

(b)

(c)

(d)

53.

Which of these is not a monomer for a high molecular mass silicone polymer?

(a)

Me₃SiCl

(b)

PhSiCl₃

(c)

MeSiCl₃

(d)

Me₂SiCl₂

54.

Among the following, which is the strongest oxidizing agent?

(a)

Cl₂

(b)

F₂

(c)

Br₂

(d)

l₂

55.

Which is true regarding nitrogen?

(a)

least electronegative element

(b)

has low ionisation enthalpy than oxygen

(c)

d- orbitals available

(d)

ability to form pπ-pπ bonds with itself

56.

Which among the following is not a borane?

(a)

B₂H₆

(b)

B₃H₆

(c)

B₄H₁₀

(d)

none of these

57.

In the Ellingham diagram, for the formation of carbon monoxide________.

(a)

\(\left( \cfrac { \Delta { S }^{ 0 } }{ \Delta T } \right) \) is negative

(b)

\(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is positive

(c)

\(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is negative

(d)

initially \(\left( \cfrac { \Delta T }{ \Delta { G }^{ 0 } } \right) \) is positive, after 700^oC,\(\left( \cfrac { \Delta { G }^{ 0 } }{ \Delta T } \right) \) is negative

58.

Which one of the following is not feasible

(a)

Zn_(s) + Cu²⁺_(aq) \(\rightarrow\) Cu_(s) + Zn²⁺_(aq)

(b)

Cu_(s)+ Zn²⁺_(aq)\(\rightarrow\) Zn_(s) + Cu²⁺_(aq)

(c)

Cu_(s) + 2Ag⁺_(ag)\(\rightarrow\) 2Ag_(s) + Cu²⁺_(aq)

(d)

Fe_(s) + Cu²⁺_(aq) \(\rightarrow\) Cu_(s)+ Fe²⁺_(aq)

Assertion and reason

2 x 2 = 4

59.

Assertion: Coagulation power of Al³⁺ is more than Na⁺.
Reason: greater the valency of the flocculating ion added, greater is its power to cause precipitation.
Codes:
a) if both assertion and reason are true and reason is the correct explanation of assertion.
b) if both assertion and reason are true but reason is not the correct explanation of assertion
c) assertion is true but reason is false
d) both assertion and reason are false

(a)

if both assertion and reason are true and reason is the correct explanation of assertion.

(b)

if both assertion and reason are true but reason is not the correct explanation of assertion

(c)

assertion is true but reason is false

(d)

both assertion and reason are false

60.

Assertion: monoclinic sulphur is an example of monoclinic crystal system
Reason: for a monoclinic system, \(a\neq b\neq c\) and \(\alpha =\gamma ={ 90 }^{ 0 },\beta \neq { 90 }^{ 0 }\)
Codes:
a) Both assertion and reason are true and reason is the correct explanation of assertion
b) Both assertion and reason are true but reason is not the correct explanation of assertion.
c) Assertion is true but reason is false.
d) Both assertion and reason are false.

(a)

Both assertion and reason are true and reason is the correct explanation of assertion

(b)

Both assertion and reason are true but reason is not the correct explanation of assertion.

(c)

Assertion is true but reason is false.

(d)

Both assertion and reason are false.

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Answers Key:

Multiple Choice Question

58 x 1 = 58

(a)
cuprous halide and halo acid

(b)
disinfectant

(d)
all of these

(b)
Sucrose

(d)
both (a) and (b)

(a)
E_measured = E_R - E_L

(b)
1.00 V

10.

11.

(a)
As₂O₃

12.

(a)
p-cresol

13.

(a)
Strong acids and strong bases

14.

15.

(a)
phenol

16.

(b)
MnSO₄

17.

(d)
PHBV

18.

19.

20.

(d)
1 and 5

21.

(b)
blue solution

22.

(d)
1,3 – dinitrobenzene

23.

24.

25.

26.

27.

(d)
x/m = PT

28.

For 1:1 electrolyte K_sp = S²
\(=[\frac{ K \times 10^{-3}}{Λ^o}]^2\)
\(=[\frac{1.85 \times 10^{-5} \times 10^{-3}}{14 \times 10^{-3}}]^2\)
= (0.1321 x 10^-3)²
= 0.01745 x 1010^-10
= 1.74 x 10^-12

29.

α = Λ/Λ^o
= 6/400
K_a = α²C
\(= \frac{6}{400} \times \frac{6}{400} \times \frac{1}{36}\)
= 6.25 x 10^-6

30.

31.

Basic buffer is the solution which has weak base and its salt.
NH₄OH + HCI → NH₄CI +H₂O + NH₄OH
200 ml 100 ml salt 100 ml weak base

32.

(d)
pseudo

33.

34.

(b)
low bond dissociation energy

35.

(a)
H₃PO₃ is dibasic and reducing

36.

(d)
both (a) & (c)

37.

(b)
λ, represents wave length of uv-rays used

38.

(b)
sheet silicates

39.

(d)
ns²np²

40.

41.

(b)
Sp³d

42.

(d)
auto

43.

(b)
roasting

44.

(a)
[Pt(NH₃)₄[[PtCl₄]

45.

46.

\({ t }_{ 1/2 }=\frac { 0.6932 }{ k } \)
For a second order reaction
\(\mathrm{t}_{1 / 2}=\frac{2^{\mathrm{n}-1}-1}{(\mathrm{n}-1) \mathrm{k} \cdot\left[\mathrm{A}_{0}\right]^{\mathrm{n}-1}}\)
n = 2
\(\mathrm{t}_{1 / 2}=\frac{2^{\mathrm{2}-1}-1}{(\mathrm{n}-1) \mathrm{k} \cdot\left[\mathrm{A}_{0}\right]^{\mathrm{2}-1}}\)
\(\mathrm{t}_{1 / 2} =\frac{1}{ \mathrm{k}\left[\mathrm{A}_{0}\right]}\)

47.

\(k=\frac { 1 }{ t } ln \frac { \left[ { A }_{ 0 } \right] }{ \left[ A \right] } \)
[A₀] = 0.1: [A] = 0.05
\(k= \left[ \frac { 1 }{ t _{1/2}} \right] ln\left[ \frac { { 0.1 } }{ 0.05 }\right] \)
\(k= \left[ \frac { 1 }{ t _{1/2}} \right] ln (2)\)
t_1/2 = In(2)/K

48.

In bcc unit cell,
2 atoms = 1 unit cell
Number of atoms in 8 g of element is, Number of moles = 8g / 40 g mol^-1 = 0.2 mol
1 mole contains 6.023 x10²³ atoms
0.2 mole contains 0.2 x 6.023 x 10²³ atoms
[1 unit cell / 2 atoms] x 0.2 x 6.023 x 10²³
= 6.023 x 10²² unit cells.

49.

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

50.

In all the complexes, the central metal ion is Co³⁺, among the given ligands CN^- is the strongest ligand, which causes large crystal
field splitting i.e maximum Δ₀

51.