12th Standard English Medium Chemistry Reduced Syllabus One mark Important Questions - 2021(Public Exam )

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Questions:

Multiple Choice Question

47 x 1 = 47

Regarding cross-linked or network polymers, which of the following statement is incorrect?

(a)

Examples are Bakelite and melamine

(b)

They are formed from bi and tri-functional monomers

(c)

They contain covalent bonds between various linear polymer chains

(d)

They contain strong covalent bonds in their polymer chain

Saccharin, an artificial sweetener is manufactured from ____________.

(a)

cellulose

(b)

toluene

(c)

cyclohexene

(d)

starch

α -D (+) Glucose and β-D (+) glucose are ______.

(a)

Epimers

(b)

Anomers

(c)

Enantiomers

(d)

Conformational isomers

Which of the following vitamins is water soluble?

(a)

Vitamin E

(b)

Vitamin K

(c)

Vitamin A

(d)

Vitamin B

The pyrimidine bases present in DNA are ______.

(a)

Cytosine and Adenine

(b)

Cytosine and Guanine

(c)

Cytosine and Thiamine

(d)

Cytosine and Uracil

\(\text { Glucose } \stackrel{(\mathrm{HCN})}{\longrightarrow} \text { Product } \stackrel{(\text { hydrolysis })}{\longrightarrow} \text { Product } \stackrel{(\mathrm{HI}+\text { Heat })}{\longrightarrow} \mathrm{A}\) , the compound A is______.

(a)

Heptanoic acid

(b)

2-Iodohexane

(c)

Heptane

(d)

Heptanol

Which one of the following is most basic?

(a)

2,4 – dichloroaniline

(b)

2,4 – dimethyl aniline

(c)

2,4 – dinitroaniline

(d)

2,4 – dibromoaniline

The order of basic strength for methyl substituted amines in aqueous solution is _________.

(a)

N(CH₃)₃> N(CH₃)₂H> N(CH₃)H₂> NH₃

(b)

N(CH₃)H₂>N(CH₃)₂H > N(CH₃)₃>NH₃

(c)

NH₃> N(CH₃)H₂> N(CH₃)₂ H>N(CH₃)₃

(d)

N(CH₃)₂H>N(CH₃)H₂> N(CH₃)₃> NH₃

Which one of the following nitro compounds does not react with nitrous acid.

(a)

CH₃ -CH₂ -CH₂ -NO₂

(b)

(CH₃)₂ CH - CH₂NO₂

(c)

(CH₃)₃C NO₂

(d)

\({ CH }_{ 3 }-\underset { \overset { || }{ O } }{ C } -\underset { \overset { || }{ { CH }_{ 3 } } }{ CH } -{ NO }_{ 2 }\)

10.

Which one of the following will not undergo Hofmann bromamide reaction.

(a)

CH₃CONHCH₃

(b)

CH₃CH₂CONH₂

(c)

CH₃CONH₂

(d)

C₆H₅CONH₂

11.

Which one of the following undergoes reaction with 50% sodium hydroxide solution to give the corresponding alcohol and acid.

(a)

Phenylmethanal

(b)

ethanal

(c)

ethanol

(d)

methanol

12.

Which of the following represents the correct order of acidity in the given compounds

(a)

FCH₂COOH > CH₃COOH > BrCH₂COOH > ClCH₂COOH

(b)

FCH₂COOH > ClCH₂COOH > BrCH₂COOH > CH₃COOH

(c)

CH₃COOH > ClCH₂COOH > FCH₂COOH > Br-CH₂COOH

(d)

Cl CH₂COOH > CH₃COOH > BrCH₂COOH > ICH₂COOH

13.

Reaction of acetone with one of the following reagents involves nucleophilic addition followed by elimination of water. The reagent is _______.

(a)

Grignard reagent

(b)

Sn / HCl

(c)

hydrazine in presence of slightly acidic solution

(d)

hydrocyanic acid

14.

The reactions
is an example of ______.

(a)

Wurtz reaction

(b)

cyclic reaction

(c)

Williamson reaction

(d)

Kolbe reactions

15.

Carbolic acid is _____.

(a)

Phenol

(b)

Picri cacid

(c)

benzoic acid

(d)

phenylacetic acid

16.

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.

17.

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

18.

The most effective electrolyte for the coagulation of As₂S₃Sol is _______.

(a)

NaCl

(b)

Ba(NO₃)₂

(c)

K₃[Fe(CN)₆]

(d)

Al₂(SO₄)₃

19.

Which one of the following is correctly matched?

(a)

Emulsion - Smoke

(b)

Gel - butter

(c)

foam - Mist

(d)

whipped cream - sol

20.

Cell equation: A + 2B^- \(\rightarrow\)A²⁺+ 2B; A²⁺ + 2e^- \(\rightarrow\)A E^o = +0.34V and log₁₀ K = 15.6 at 300K for cell reactions find E^o for B⁺ + e⁻ \(\rightarrow\) B

(a)

0.80

(b)

1.26

(c)

-0.54

(d)

-10.94

21.

The number of electrons delivered at the cathode during electrolysis by a current of 1A in 60 seconds is ____. (charge of electron = 1.6 ×10⁻¹⁹C )

(a)

6.22 ×10²³

(b)

6.022 ×10²⁰

(c)

3.75 ×10²⁰

(d)

7.48 ×10²³

22.

The molar conductivity of a 0.5 mol dm^-3 solution of AgNO₃ with electrolytic conductivity of 5.76 ×10⁻³ S cm⁻¹at 298 K is______.

(a)

2.88 S cm²mol^-1

(b)

11.52 S cm²mol^-1

(c)

0.086 S cm²mol^-1

(d)

28.8 S cm²mol^-1

23.

The hydrogen ion concentration of a buffer solution consisting of a weak acid and its salts is given by _______.

(a)

\([{ H }^{ + }]=\frac { { K }_{ a }[acid] }{ [salt] } \)

(b)

\([{ H }^{ + }]={ K }_{ a }[salt]\)

(c)

\([{ H }^{ + }]={ K }_{ a }[acid]\)

(d)

\([{ H }^{ + }]=\frac { { K }_{ a }[salt] }{ [acid] } \)

24.

What is the pH of the resulting solution when equal volumes of 0.1M NaOH and 0.01M HCl are mixed?

(a)

2.0

(b)

(c)

7.0

(d)

12.65

25.

The aqueous solutions of sodium formate, anilinium chloride and potassium cyanide are respectively _______.

(a)

acidic, acidic, basic

(b)

basic, acidic, basic

(c)

basic, neutral, basic

(d)

none of these

26.

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

27.

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.

28.

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

29.

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

30.

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

31.

The crystal with a metal deficiency defect is ________.

(a)

NaCl

(b)

FeO

(c)

ZnO

(d)

KCl

32.

The yellow colour in NaCl crystal is due to ________.

(a)

excitation of electrons in F centers

(b)

reflection of light from Cl^- ion on the surface

(c)

refraction of light from Na⁺ ion

(d)

all of the above

33.

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)

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

34.

The ratio of close packed atoms to tetrahedral hole in cubic packing is ________.

(a)

1:1

(b)

1:2

(c)

2:1

(d)

1:4

35.

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-

36.

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

37.

A complex has a molecular formula MSO₄Cl.6H₂O. The aqueous solution of it gives white precipitate with Barium chloride solution and no precipitate is obtained when it is treated with silver nitrate solution. If the secondary valence of the metal is six, which one of the following correctly represents the complex?

(a)

[M(H₂O)₄Cl]SO₄.2H₂O

(b)

[M(H₂O)₆]SO₄

(c)

[M(H₂O)₅Cl]SO₄.H₂O

(d)

[M(H₂O)₃Cl]SO₄.3H₂O

38.

The most common oxidation state of actinoids is _______.

(a)

(b)

(c)

(d)

39.

MnO₄^- react with Br^- in alkaline P^H to give ________.

(a)

BrO₃^- MnO₂

(b)

Br₂, MnO₄^2-

(c)

Br₂, MnO₂

(d)

BrO^-, MnO₄^2-

40.

Which of the following does not give oxygen on heating?

(a)

K₂Cr₂O₇

(b)

(NH₄)₂Cr₂O₇

(c)

KClO₃

(d)

Zn(ClO₃)₂

41.

AlF₃ is soluble in HF only in the presence of KF. It is due to the formation of _________.

(a)

K₃[AIF₃H₃]

(b)

K₃[AiF₆]

(c)

AIH₃

(d)

K[AIF₃H]

42.

When copper is heated with conc HNO₃ it produces ________.

(a)

Cu(NO₃)₂, NO and NO₂

(b)

Cu(NO₃)₂ and N₂O

(c)

Cu(NO₃)₂ and NO₂

(d)

Cu(NO₃)₂ and NO

43.

Among the following, which is the strongest oxidizing agent?

(a)

Cl₂

(b)

F₂

(c)

Br₂

(d)

l₂

44.

P₄O₆ reacts with cold water to give _______.

(a)

H₃PO₃

(b)

H₄P₂O₇

(c)

HPO₃

(d)

H₃PO₄

45.

An aqueous solution of borax is________.

(a)

neutral

(b)

acidic

(c)

basic

(d)

amphoteric

46.

In the extraction of aluminium from alumina by electrolysis, cryolite is added to_______.

(a)

Lower the melting point of alumina

(b)

Remove impurities from alumina

(c)

Decrease the electrical conductivity

(d)

Increase the rate of reduction

47.

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)

Assertion and reason

3 x 2 = 6

48.

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.

49.

Assertion: pure iron when heated in dry air is converted with a layer of rust.
Reason: Rust has the composition Fe₃ O₄
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

50.

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

47 x 1 = 47

(d)
They contain strong covalent bonds in their polymer chain

(b)
toluene

(b)
Anomers

(d)
Vitamin B

(a)
Heptanoic acid

(b)
2,4 – dimethyl aniline

(d)
N(CH₃)₂H>N(CH₃)H₂> N(CH₃)₃> NH₃

10.

(a)
CH₃CONHCH₃

11.

12.

- I etiect increases the acidity. If electronegativity is high, - I effect is also high.

13.

14.

15.

(a)
Phenol

16.

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

17.

(d)
x/m = PT

18.

As₂S₃ is a negatively charged colloid. It will be most effectively coagulated by the cation with greater valency. i.e., Al³⁺.

19.

(b)
Gel - butter

20.

(a)
0.80

21.

Q = It
= 1A x 60s = 60 C
96500 C charge = 6.023 x 10²³ electrons
60 C charge \(= \frac{6.023 \times 10^{23}}{96500}\times 60\)
= 3.744 x 10²⁰ electrons

22.

Λ = k/W x 10⁻³ mol⁻¹ dm³
\(=\frac{ 5.76 \times 10^{−3} S cm^{−1} \times 10^{−3}}{0.5} = mol^{-1} dm^{3}\)
\(=\frac{ 5.76 \times 10^{−3} S cm^{−1} \times 10^{−3}}{0.5}\) S cm^-1 mol⁻¹ dm³
= 11.52 S cm²mol^-1

23.

According to Henderson equation
pH = pK_a+ log [Acid]/[Salt]
i.e., -log [H⁺] = - log K_a + log [Acid]/[Salt]
-log [H⁺] = log [Acid]/[Salt] x 1/ K_a
log 1/[H⁺] = log [Acid]/[Salt] x 1/ K_a
[H⁺] = K_a [Acid]/[Salt]

24.

x ml of 0.1 M NaOH + x mL of 0.01 M HCI
No. of moles of NaOH = 0.1 x X x 10^-3
= 0.1 X x 10^-3
No. of moles of HCI = 0.01 x X x 10^-3
= 0.01 X x 10^-3
No. of moles of NaOH after mixing
= 0.1 X x 10^-3 - 0.01 X x 10^-3
= 0.09 X x 10^-3
Concentration of NaOH\(= (\frac{0.09x \times 10^{-3}}{2x \times 10^{-3}}) = 0 .045\)
[OH^-] = 0.045
pOH =-log (4.5 x 10^-2)
= 2 -log 4.5
= 2 - 0.65 = 1.35
pH = 14 - 1.35 = 12.65

25.

HCOONa + HOH ⇌ NaOH + H-COOH
strong base weak acid
Basic in nature.
C₆H₅NH₃Cl + HOH ⇌ H₃O⁺ + C₆H₅ - NH₂ + Cl^-
acidic
KCN + H - OH ⇌ KOH + HCN
Base strong base weak acid
basic, acidic, basic is correct.

26.

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

27.

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

28.

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

29.

30.

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

31.

(b)
FeO

32.

(a)
excitation of electrons in F centers

33.

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

34.

If number of close packed atoms = N, then
The number of Tetrahedral holes formed = 2N
The number of Octahedral holes formed = N
Therefore, N:2N = 1:2

35.

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

36.

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

37.

Molecular formula: MSO₄Cl.6H₂O
Formation of white precipitate with Barium chloride indicates that SO^2-₄ ions are outside the coordination sphere, and no precipitate with AgNO₃ solution indicates that the Cl^- ions are inside the coordination sphere. Since the coordination number of M is 6.Cl^- and 5 H₂O are ligands, remaining 1 H₂O molecular and SO^2-₄ are in the outer coordination sphere.