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

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

When phenol reacts with CCl₄and NaOH, the product formed is ________ acid.

(a)

salicylic

(b)

cinnamic

(c)

benzoic

(d)

carboxylic

Formation of o and p - hydroxy benzaldehyde from phenol on treatment with CHCl₃ and NaOH is _______.

(a)

Riemer-Tiemann reaction

(b)

Kolbe's reaction

(c)

Coupling reaction

(d)

Hydrogenation

Ethers in the presence of atmospheric oxygen oxidises to give hydroperoxides and dialkyl peroxides Such a spontaneous reaction by atmospheric oxygen is called ______.

(a)

auto oxidation

(b)

acylation

(c)

alkylation

(d)

dehydration

CH₂= CH₂+H₂O The above reaction is _______.

(a)

Lucas test

(b)

Saponification

(c)

Victor Meyer's test

(d)

hydroxylation

Compound of molecular formula C₇H₈O is a sweet smeeling liquid. A on reaction with acidified K₂Cr₂O₇ gives compound B of molecular formula C₇H₈O. B reduces Tollen's reagent A and B are respectively.

(a)

benzaldelyde and benzoic acid

(b)

Methyl phenykarbinol and acetophenone

(c)

benzyl alcohol and benzaldehyde

(d)

diphenyl carbinol and benzophenone

The ionization constant of phenol is higher than that of ethanol because ______.

(a)

phenoxide ion is bulkier than ethoxide

(b)

phenoxide ion is stronger base than ethoxide.

(c)

phenoxide ion is stablized through delocalisation.

(d)

phenoxide ion is less stable than ethoxide ion.

In aqueous solution of amino acids mostly exists in ______.

(a)

NH₂-CH(R)-COOH

(b)

NH₂-CH(R)-COO^-

(c)

H₃N⁺-CH(R)-COOH

(d)

H₃N⁺-CH(R)-COO^-

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

The formation of cyanohydrin from acetone is an example of _______.

(a)

nucleophilic substitution

(b)

electrophilic substitution

(c)

electrophilic addition

(d)

Nucleophilic addition

10.

Among the following ethers which one will produce methyl alcohol on treatment with hot HI?

(a)

(H₃C)₃C-O-CH₃

(b)

(CH₃-)₂-CH-CH₂-O-CH₃

(c)

CH₃-(CH₂)₃-O-CH₃

(d)

CH₃-CH₂-\(\underset { \overset { | }{ { CH }_{ 3 } } }{ CH } \)-O-CH₃

11.

The correct IUPAC name of the compound

(a)

4 – chloro – 2,3 – dimethyl pentan – 1-ol

(b)

2,3 – dimethyl – 4- chloropentan -1-ol

(c)

2,3,4 – trimethyl – 4- chlorobutan -1-ol

(d)

4– chloro – 2,3,4 – trimethyl pentan – 1-ol

12.

On which of the following properties does the coagulating power of an ion depend?

(a)

Both magnitude and sign of the charge on the ion.

(b)

Size of the ion alone

(c)

the magnitude of the charge on the ion alone

(d)

the sign of charge on the ion alone.

13.

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

14.

Electrolyte	KCl	KNO₃	HCl	NaOAC	NaCl
Λ_- (Scm² mol^-1)	149.9	145.0	426.2	91.0	126.5

Calculate Λ^o_HoAC using appropriate molar conductances of the electrolytes listed above at infinite dilution in water at 25^oC_______.

(a)

517.2

(b)

552.7

(c)

390.7

(d)

217.5

15.

The solubility of BaSO₄ in water is 2.42 × 10^-3gL^-1 at 298K. The value of its solubility product(K_sp) will be (Given molar mass of BaSO₄ =233g mol^-1)

(a)

1.08 × 10^-14mol²L^-2

(b)

1.08 × 10^-12mol²L^-2

(c)

1.08 × 10^-10mol²L^-2

(d)

1.08 × 10^-8mol²L^-2

16.

In a homogeneous reaction A⟶B+C+D, the initial pressure was P₀ and after time t it was P expression for rate constant in terms of P₀, P and t will be _____.

(a)

\(k=\left( \frac { 2.303 }{ t } \right) \log\left( \frac { 2{ P }_{ 0 } }{ { 3P }_{ 0 }-P } \right) \)

(b)

\(k=\left( \frac { 2.303 }{ t } \right) \log\left( \frac { { 2P }_{ 0 } }{ { P }_{ 0 }-P } \right) \)

(c)

\(k=\left( \frac { 2.303 }{ t } \right) \log\left( \frac { 3{ P }_{ 0 }-P }{ 2P_{ 0 } } \right) \)

(d)

\(k=\left( \frac { 2.303 }{ t } \right) \log\left( \frac { 2{ P }_{ 0 } }{ { 3P }_{ 0 }-2P } \right) \)

17.

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

18.

CsCl has bcc arrangement, its unit cell edge length is 400pm, its inter atomic distance is ________.

(a)

400pm

(b)

800pm

(c)

\(\sqrt { 3 } \times 100pm\)

(d)

\(\left( \frac { \sqrt { 3 } }{ 2 } \right) \times 400pm\)

19.

Choose the correct statement.

(a)

Square planar complexes are more stable than octahedral complexes

(b)

The spin only magnetic moment of [Cu(Cl)₄]^2- is BM and it has square planar structure.

(c)

Crystal field splitting energy \(\left( { \Delta }_{ 0 } \right) \) [FeF₆]^4- is higher than the \((\Delta _{ 0 })\) of [Fe(CN)₆]^4-

(d)

crystal field stabilization energy of [V(H₂O)₆]²⁺ is higher than the crystal field stabilization of [Ti(H₂O)₆]²⁺

20.

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

21.

In acid medium, potassium permanganate oxidizes oxalic acid to _______.

(a)

oxalate

(b)

Carbon dioxide

(c)

acetate

(d)

acetic acid

22.

Duralumin is an alloy of ______.

(a)

Cu, Mn

(b)

Cu, Al, Mg

(c)

Al, Mn

(d)

Al, Cu, Mn, Mg

23.

Most easily liquefiable gas is _______.

(a)

(b)

(c)

(d)

24.

On hydrolysis, PCl₃ gives________.

(a)

H₃PO₃

(b)

PH₃

(c)

H₃PO₄

(d)

POCl₃

Assertion and reason

1 x 2 = 2

25.

Assertion: Phenol is more reactive than benzene towards electrophilic substitution reaction
Reason: In the case of phenol, the intermediate arenium ion is more stabilized by resonance
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.

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Answers Key:

Multiple Choice Question

24 x 1 = 24

(a)
salicylic

(a)
Riemer-Tiemann reaction

(a)
auto oxidation

(d)
hydroxylation

(d)
H₃N⁺-CH(R)-COO^-

(d)
Nucleophilic addition

10.

11.

(a)
4 – chloro – 2,3 – dimethyl pentan – 1-ol

12.

(a)
Both magnitude and sign of the charge on the ion.

13.

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

14.

(Λ^o_HoAC) = [(Λ^o)_HCl + Λ^o)_NaOAC ] - (Λ^o)_NaCl
= (426.2 + 91) - (126.5)
= 390.7

15.

BaSO₄ ⇌ Ba²⁺ + SO₄^2-
K_sp = (s) (s)
K_sp = (s)²
= (2.42 × 10^-3gL^-1)²
\(=\frac{2.42 \times 10^{-3} gL^{-1}}{233 \text{ g mol}^{-1}}\)
= (0.01038 x 10^-3)²
= (1.038 x x 10^-5)²
= 1.077 x 10^-10
= 1.08 × 10^-10mol²L^-2

16.

	A	⟶	B	C	D
Initial rate (M s^-1)	a		0	0	0
Reaction number	x	-	-	-	-
After time t	(a - x)		x	x	x
Total number of moles	= (a + 2x)

17.

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

18.

\(3 \sqrt{a} = r_{C_{s+}} + 2r_{C_{f-}} + r_{C_{s+}} \)
\(\left( \frac { \sqrt { 3 } }{ 2 } \right) a = r_{C_{s+}} + r_{C_{f-}} \)
\(\left( \frac { \sqrt { 3 } }{ 2 } \right) \times 400\)= inter ionic distance

19.