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

12th Standard

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 50

Part A

50 x 1 = 50
1. Which one of the following reaction represents calcinations?

(a)

$2Zn+{ O }_{ 2 }\rightarrow 2ZnO$

(b)

$2ZnS+3O_{ 2 }\rightarrow 2ZnS+3O_{ 2 }\rightarrow 2ZnO_{ 2 }\rightarrow 2ZnO+2SO_{ 2 }$

(c)

$MgCO_{ 3 }\rightarrow MgO+CO_{ 2 }$

(d)

Both (a) and (c)

2. 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

3. An aqueous solution of borax is

(a)

neutral

(b)

acidic

(c)

basic

(d)

amphoteric

4. AlF3 is soluble in HF only in the presence of KF. It is due to the formation of (NEET)

(a)

K3[AIF3H3]

(b)

K3[AiF6]

(c)

AIH3

(d)

K[AIF3H]

5. P4O6 reacts with cold water to give

(a)

H3PO3

(b)

H4P2O7

(c)

HPO3

(d)

H3PO4

6. Among the following, which is the strongest oxidizing agent?

(a)

Cl2

(b)

F2

(c)

Br2

(d)

l2

7. 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

8. Which of the following does not give oxygen on heating?

(a)

K2Cr2O7

(b)

(NH4)2Cr2O7

(c)

KClO3

(d)

Zn(ClO3)2

9. MnO4- react with Br- in alkaline PH to give

(a)

BrO3- MnO2

(b)

Br2, MnO42-

(c)

Br2, MnO2

(d)

BrO-, MnO42-

10. The most common oxidation state of actinoids is

(a)

+2

(b)

+3

(c)

+4

(d)

+6

11. A complex has a molecular formula MSOCl. 6HO42.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]SO42H2O

(b)

[M(H2O)6]SO4

(c)

[M(H2O)5Cl]SO4H2O

(d)

[M(H2O)3Cl]SO4.3H2O

12. 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

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

(a)

[Ni(NH3)4(H2O)2]2+

(b)

<>

(c)

[Co(NH3)5SO4]Cl

(d)

[Fe(en)3]3+

14. 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

15. 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.

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

(a)

$\left( \cfrac { 100 }{ 0.414 } \right)$

(b)

$\left( \cfrac { 0.732 }{ 100 } \right)$

(c)

100X0.414

(d)

$\left( \cfrac { 0.414 }{ 100 } \right)$

17. 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

18. The crystal with a metal deficiency defect is

(a)

NaCl

(b)

FeO

(c)

ZnO

(d)

KCl

19. The addition of a catalyst during a chemical reaction alters which of the following quantities? (NEET)

(a)

Enthalpy

(b)

Activation energy

(c)

Entropy

(d)

Internal energy

20. In a reversible reaction, the enthalpy change and the activation energy in the forward direction are respectively −x kJ mol-4 and 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 103Jmol-1

21. 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

22. The correct difference between first and second order reactions is that (NEET)

(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.

23. The solubility of BaSO4 in water is 2.42 ×10-3gL-1 at 298K. The value of its solubility product(Ksp) will be (Given molar mass of BaSO4 =233g mol 4-1)

(a)

1.08 ×10-14mol2L-2

(b)

1.08 ×10-12mol2L-2

(c)

1.08 ×10-10mol2L-2

(d)

1.08 ×10-8mol2L-2

24. 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

25. 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)

3

(c)

7.0

(d)

12.65

26. 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)

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

27. 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 cm2 mol -1

28. 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

29. 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

30. Cell equation : A + 2B- $\rightarrow$A2++2B;
A2+ + 2e- $\rightarrow$AEo =+0.34V and log10 K = 15.6 at 300K for cell reactions find Eo for
B1 + e $\rightarrow$

(a)

0.80

(b)

1.26

(c)

-0.54

(d)

-10.94

31. Which one of the following is correctly matched?

(a)

Emulsion - Smoke

(b)

Gel - butter

(c)

foam - Mist

(d)

whipped cream - sol

32. The most effective electrolyte for the coagulation of AS2S3Sol is

(a)

NaCl

(b)

Ba(NO3)2

(c)

K3[Fe(CN)6]

(d)

Al3+

33. 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

34. 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.

35. Carbolic acid is

(a)

Phenol

(b)

Picri cacid

(c)

benzoic acid

(d)

phenylacetic acid

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

37. The reactions
is an example of

(a)

Wurtz reaction

(b)

cyclic reaction

(c)

Williamson reaction

(d)

Kolbe reactions

38. 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

39. 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

40. 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

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

(a)

CH3CONHCH3

(b)

CH3 CH2CONH2

(c)

CH3CONH2

(d)

C6H5CONH2

42. 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)3 C NO2

(d)

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

43. 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

44. 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

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

(a)

Heptanoic acid

(b)

2-Iodohexane

(c)

Heptane

(d)

Heptanol

46. The pyrimidine bases present in DNA are

(a)

Cytosine and Adenine

(b)

Cytosine and Guanine

(c)

Cytosine and Thiamine

(d)

Cytosine and Uracil

47. Which of the following vitamins is water soluble?

(a)

Vitamin E

(b)

Vitamin K

(c)

Vitamin A

(d)

Vitamin B

48. $\alpha$-D (+) Glucose and β-D (+) glucose are

(a)

Epimers

(b)

Anomers

(c)

Enantiomers

(d)

Conformational isomers

49. Saccharin, an artificial sweetener is manufactured from ____________.

(a)

cellulose

(b)

toluene

(c)

cyclohexene

(d)

starch

50. 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