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12th Standard Chemistry English Medium Free Online Test One Mark Questions with Answer Key 2020 - Part Three

Published on: 13/10/2020

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.

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Std: 12th Standard - Chemistry

chapter: - Model Question paper

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Questions:

Multiple Choice Question

24 x 1 = 24

Nitrobenzene on electrolytic reduction in con. sulphuric acid, the intermediate formed is

(a)

C₆H₅NH - NHC₆H₅

(b)

C₆H₅ - NHOH

(c)

C₆H₅ - N = N - C₆H₅

(d)

C₆H₅HSO₄

Cholesterol is an example of _________.

(a)

protein

(b)

vitamin

(c)

carbohydrat

(d)

lipid

Amino acids are linked covalently by ________bonds.

(a)

hydrogen

(b)

Co-ordinate

(c)

both (a) and (b)

(d)

peptide

Sucrose contains glucose and fructose linked by

(a)

C₁ - C₁

(b)

C₁- C₂

(c)

C₁ - C₄

(d)

C₁ - C₆

The metal to be protected from corrosion is treated with cone HNO₃ The process is called ________.

(a)

galvanize

(b)

passivation

(c)

cathodic protection

(d)

formation of alloys

\(Phenol\overset { Zn }{ \underset { dust }{ \longrightarrow } } 'X'\overset { { CH }_{ 3 }Cl }{ \underset { anhy\ AlC{ I }_{ 3 } }{ \longrightarrow } } Y\overset { alk }{ \underset { { KMnO }_{ 4 } }{ \longrightarrow Z } } \) the product Z is __________.

(a)

benzaldehyde

(b)

benzoic acid

(c)

benzone

(d)

toluene

Identify 'X'.

(a)

(b)

(c)

(d)

A solution which is resistant to changes of pH on addition of small amounts of an acid or a base is known as _______.

(a)

buffer solution

(b)

true solution

(c)

Isohydric solution ideal solution

(d)

ideal solution

is __________

(a)

Mesitylene

(b)

Pyrogallol

(c)

Hydroxy quinol

(d)

Phluroglucinol

10.

Identify X in the sequence give below

(a)

(b)

(c)

(d)

11.

Which one of the following reduces tollens reagent

(a)

formic acid

(b)

acetic acid

(c)

benzophenone

(d)

none of these

12.

Which one of the is not a surfactant?

(a)

CH₃ -(CH₂)₁₅ -N⁺ -(CH₃)₂ CH₂Br

(b)

CH₃ -(CH₂)₁₅ -NH₂

(c)

CH₃ -(- CH₂- )-₁₆CH₂ OSO₂^- Na⁺

(d)

OHC-(CH₂)₁₄ -CH₂ -COO^- Na⁺

13.

During decomposition of an activated complex.

(a)

energy is always released

(b)

energy is always absorbed

(c)

energy does not change

(d)

products may be formed.

14.

A binary solid A+B has a structure with B^- ions constituting the lattice and A⁺ ions occupying 25% tetrahedral holes. Formula of the solid is _______.

(a)

A₂B

(b)

AB₂

(c)

(d)

AB₄

15.

Identify the metal that occurs in free state.

(a)

(b)

(c)

(d)

16.

Werner's theory was not able to explain_______ of coordination compounds.

(a)

colour

(b)

magnetic properties

(c)

both (a) and (b)

(d)

neither (a) nor (b)

17.

Co-ordination isomerism is exhibited by _______.

(a)

[Cr(en)₂Cl₂]NO₂

(b)

[Pt(NH₃)₄] [CuCl₄]

(c)

[Cr(en)₂Cl₂]NO

(d)

[Co(NH₃)₅Cl]Cl₂

18.

The addition of a catalyst during a chemical reaction alters which of the following quantities?

(a)

Enthalpy

(b)

Activation energy

(c)

Entropy

(d)

Internal energy

19.

The crystal with a metal deficiency defect is ________.

(a)

NaCl

(b)

FeO

(c)

ZnO

(d)

KCl

20.

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)

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

21.

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⁺

22.

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

23.

Which of the following is not sp² hybridised?

(a)

Graphite

(b)

graphene

(c)

Fullerene

(d)

dry ice

24.

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

(a)

(b)

(c)

(d)

Assertion and reason

1 x 2 = 2

25.

Assertion: Phenol is more acidic than ethanol
Reason: Phenoxide ion is resonance stabilized
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)

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.

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Answers Key:

Multiple Choice Question

24 x 1 = 24

(b)
C₆H₅ - NHOH

(d)
lipid

(d)
peptide

(b)
C₁- C₂

(b)
passivation

(b)
benzoic acid

(a)
buffer solution

(d)
Phluroglucinol

10.

11.

12.

(b)
CH₃ -(CH₂)₁₅ -NH₂

13.

(a)
energy is always released

14.

(b)
AB₂

15.

(b)
Au

16.

17.

(b)
[Pt(NH₃)₄] [CuCl₄]

18.

A catalyst provides a new path to the reaction with low activation energy. i.e., it lowers the activation energy.

19.

(b)
FeO

20.

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.

21.

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

22.

23.