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#### Important 1 Mark Book Back Questions (New Syllabus) 2020

12th Standard EM

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Chemistry

Time : 00:30:00 Hrs
Total Marks : 36

Part A

36 x 1 = 36
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. Which one of the following is not feasible

(a)

$Zn(s)+C{ u }^{ 2+ }\left( aq \right) \rightarrow Cu\left( s \right) +{ Zn }^{ 2+ }(aq)$

(b)

$Cu(s)+Z{ n }^{ 2+ }(aq)\longrightarrow Zn(s)+{ Cu }^{ 2+ }(aq)$

(c)

$Cu(s)+2Ag^{ + }(aq)\longrightarrow Ag(s)+{ Cu }^{ 2+ }(aq)$

(d)

$Fe(s)+{ Cu }^{ 2+ }(aq)\longrightarrow Cu(s)+{ Fe }^{ 2+ }(aq)$

3. Which of the following metals has the largest abundance in the earth’s crust?

(a)

Aluminium

(b)

calcium

(c)

Magnesium

(d)

sodium

4. The basic structural unit of silicates is (NEET)

(a)

$\left( SiO_{ 3 } \right) ^{ 2- }$

(b)

$\left( SiO_{ 4 } \right) ^{ 2- }$

(c)

$\left( Sio \right) ^{ - }$

(d)

$\left( SiO_{ 4 } \right) ^{ 4- }$

5. Duralumin is an alloy of

(a)

Cu,Mn

(b)

Cu,Al,Mg

(c)

Al,Mn

(d)

Al,Cu,Mn,Mg

6. On hydrolysis, PCl3 gives

(a)

H3PO3

(b)

PH3

(c)

H3PO4

(d)

POCl3

7. Assertion : bond dissociation energy of fluorine is greater than chlorine gas
Reason: chlorine has more electronic repulsion than fluorine.

(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

8. Which of the following d block element has half filled penultimate d sub shell as well as half filled valence sub shell?

(a)

Cr

(b)

Pd

(c)

Pt

(d)

none of these

9. Which of the following compounds is colourless?

(a)

Fe3+

(b)

Ti4+

(c)

Co2+

(d)

Ni2+

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

(a)

BrO3- MnO2

(b)

Br2, MnO42-

(c)

Br2, MnO2

(d)

BrO-, MnO42-

11. Which one of the following statements related to lanthanons is incorrect?

(a)

Europium shows +2 oxidation state

(b)

The basicity decreases as the ionic radius decreases from Pr to Lu.

(c)

All the lanthanons are much more reactive than aluminium

(d)

Ce4+ solutions are widely used as oxidising agents in volumetric analysis.

12. An excess of silver nitrate is added to 100ml of a 0.01M solution of pentaaquachloridochromium(III)chloride. The number of moles of AgCl precipitated would be

(a)

0.02

(b)

0.002

(c)

0.01

(d)

0.2

13. Oxidation state of Iron and the charge on the ligand NO in [Fe(H2O)5NO]SO4 are

(a)

+2 and 0 respectively

(b)

+3 and 0 respectively

(c)

+3 and -1 respectively

(d)

+1 and +1 respectively

14. Which kind of isomerism is possible for a complex<<EVA039.eps>>?

(a)

geometrical and ionization

(b)

geometrical and optical

(c)

optical and ionization

(d)

geometrical only

15. Solid CO2 is an example of

(a)

Covalent solid

(b)

metallic solid

(c)

molecular solid

(d)

ionic solid

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

(a)

6.023 X 1023

(b)

6.023 X 1022

(c)

60.23 X 1023

(d)

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

17. if ‘a’ is the length of the side of the cube, the distance between the body centered atom and one corner atom in the cube will be

(a)

$\left( \cfrac { 2 }{ \sqrt { 3 } } \right) a$

(b)

$\left( \cfrac { 4 }{ \sqrt { 3 } } \right) a$

(c)

$\left( \cfrac { \sqrt { 3 } }{ 4 } \right) a$

(d)

$\left( \cfrac { \sqrt { 3 } }{ 2 } \right) a$

18. 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, t1/2 cannot be determined from the given data

19. Assertion: rate of reaction doubles when the concentration of the reactant is doubles if it is a first order reaction.
Reason: rate constant also doubles

(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.

20. 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

21. The button cell used is watches function as follows
Zn (s) + Ag2O (s) + H2O (l) ⇌ 2Ag (s) + Zn2+ (aq) + 2OH-(aq)the half cell potentials
are Ag2 O (s) + H2O (l) + 2e- →2Ag (s) + 2OH- (aq) Eo.34V The cell potential will be

(a)

0.84V

(b)

1.34V

(c)

1.10V

(d)

0.42V

22. 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 (Aom)AB = 14 ×10−3Sm2 mol−1.

(a)

5.7 x10 -12

(b)

1.32×10−12

(c)

7.5 ×10−12

(d)

1.74 x10 -12

23. Statement :
To stop bleeding from an injury, ferric chloride can be applied. Which comment about the statement is justified?

(a)

It is not true, ferric chloride is a poison.

(b)

It is true, Fe3+ ions coagulate blood which is a negatively charged sol

(c)

It is not true; ferric chloride is ionic and gets into the blood stream.

(d)

It is true, coagulation takes place because of formation of negatively charged sol with Cl-.

24. Match the following

 a V2O5 i High density polyethylene b Ziegler – Natta ii PAN c Peroxide iii NH3 d Finely divided Fe iv H2SO4
(a)
 A B C D iv i ii iii
(b)
 A B C D i ii iv iii
(c)
 A B C D ii iii iv i
(d)
 A B C D iii iv ii i
25. Which of the following compounds on reaction with methyl magnesium bromide will give tertiary alcohol.

(a)

benzaldehyde

(b)

propanoic acid

(c)

methyl propanoate

(d)

acetaldehyde

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. Williamson synthesis of preparing dimethyl ether is a / an /

(a)

SN1 reactions

(b)

SN2 reaction

(c)

electrophilic addition

(d)

electrophilic substitution

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

(a)

(CH3)2 C(OH)C6H5

(b)

CH3CH(OH)C6H5

(c)

CH3CH(OH)CH2- CH3

(d)

29. The reagent used to distinguish between acetaldehyde and benzaldehyde is

(a)

Tollens reagent

(b)

Fehling’s solution

(c)

2,4 – dinitrophenyl hydrazine

(d)

semicarbazide

30. In which of the following reactions new carbon – carbon bond is not formed?

(a)

Aldol condensation

(b)

Friedel craft reaction

(c)

Kolbe’s reaction

(d)

Wolf kishner reduction

31. Aniline + benzoylchloride $\overset { NaOH }{ \longrightarrow }$C6H5 - NH - COC H this reaction is known as

(a)

Friedel – crafts reaction

(b)

HVZ reaction

(c)

Schotten – Baumann reaction

(d)

none of these

32. The product formed by the reaction an aldehyde with a prmary amine

(a)

carboxylic acid

(b)

aromatic acid

(c)

schiff ’s base

(d)

ketone

33. Assertion: A solution of sucrose in water is dextrorotatory. But on hydrolysis in the presence of little hydrochloric acid, it becomes levorotatory. (AIIMS)
Reason: Sucrose hydrolysis gives unequal amounts of glucose and fructose. As a result of this change in sign of rotation is observed.

(a)

If both accretion 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)

If assertion is true but reason is false.

(d)

if both assertion and reason are false.

34. The correct statement regarding RNA and DNA respectively is

(a)

the sugar component in RNA is an arabinos and the sugar component in DNA is ribose

(b)

the sugar component in RNA is 2’-deoxyribose and the sugar component in DNA is arabinose

(c)

the sugar component in RNA is an arabinose and the sugar component in DNA is 2’-deoxyribose

(d)

the sugar component in RNA is ribose and the sugar component in DNA is 2’-deoxyribose

35. Antiseptics and disinfectants either kill or prevent growth of microorganisms. Identify which of the following statement is not true

(a)

dilute solutions of boric acid and hydrogen peroxide are strong antiseptics.

(b)

Disinfectants harm the living tissues

(c)

A 0.2% solution of phenol is an antiseptic while 1% solution acts as a disinfectant.

(d)

Chlorine and iodine are used as strong disinfectants

36. Drugs that bind to the receptor site and inhibit its natural function are called

(a)

antagonists

(b)

agonists

(c)

enzymes

(d)

molecular targets