Chemistry

Single correct answer type:

1. The relative reactivities of acyl compounds towards nucleophilic substitution are in

the order of

(A) acyl chloride > acid anhydride > ester > amide

(B) ester > acyl chloride > amide > acid anhydride

(C) acid anhydride > amide > ester > acyl chloride

(D) acyl chloride > ester > acid anhydride > amide

Solution: (A)

The ease of nucleophilic substitution is depend upon the nature of leaving group. When

the leaving tendency of a group in a compound is high, then the compound is more

reactive towards nucleophilic substitution.

The nucleophilic acyl substitution is completed in two steps as shown below

The reactivity of the compound may be explained on the basicity of the leaving group. A

weaker base is a better leaving group. The basicity order is as

and therefore, the order of reactivity of acyl compound is as

Acyl chloride > Acid anhydride > Ester > Amide

2. Clemmensen reduction of a ketone is carried out in the presence of which of the

following?

(A) Zn-Hg with

(B)

(C) and Pt as catalyst

(D)Glycol with KOH

Solution: (A)

The reducing agent used in Clemmensen reduction is Zn-Hg and . It converts

group into group.

3. In Duma’s method of estimation of nitrogen, 0.35g of an organic compound gave

55mL of nitrogen collected at 300K temperature and 715 mm pressure. The percentage

composition of nitrogen in the compound would be (Aqueous tension at 300 K = 15 mm)

(A) 16.45 (B) 17.45 (C) 14.45 (D) 15.45

Solution: (A)

Or ( )

Where,

(Pressure at which collected)

aqueous tension of water = 15 mm

Volume of moist nitrogen in nitrometer

Pressure of at STP = 760 mm

temperature of at STP = 273 K

( )

% of nitrogen in the given compound

4. Which of the following is not correct?

(A) Ammonia is used as refrigerant

(B) A mixture of ( ) and C is known as nitrolim

(C) A mixture of ( ) and is known as superphosphate of lime

(D) Hydrolysis of gives and

Solution: (B)

A mixture of calcium cyanamide and coke ( ) is called nitrolim. It is used as a

fertilizer and can be prepared by passing nitrogen on

5. Which one of the following aromatic?

(A) Cyclopentadienyl cation

(B) Cyclooctatetraene

(C) Cycloheptatriene

(D) Cycloheptatrienylcation

Solution: (D)

6. The complexes [ ( ) ] [ ( ) ] and [ ( ) ] [ ( ) ] are the examples of

which type of isomerism?

(A) Ionisation isomerism

(B) Coordination isomerism

(C) Geometrical isomerism

(D) Linkage isomerism

Solution: (B)

The complexes [ ( ) ] [ ( ) ] and [ ( ) ] [ ( ) ] are the examples of

coordination isomerisms. This isomerism occurs only in those complexes in which both

cation and anion are complex. It occurs due to exchange of ligands between cation and

anion.

7. A solution with negative deviation among the following is

(A) Ethanol-acetone

(B) Chlorobenzene-bromobenzene

(C) Chloroform-acetone

(D) Benzene-toluene

Solution: (C)

When the attraction forces between the two components of a solution are greater than

that between the components themselves, the obtained solution exhibit negative

deviation from Raoult’s law. In case of solution of chloroform and acetone, the forces of

attraction between chloroform and acetone is greater than that exists between the

molecules of chloroform or between the molecules of acetone, thus this solution shows

negative deviation.

8. Which of the following compounds is soluble in benzene but almost insoluble in

water?

(A) (B)

(C) (D)

Solution: (D)

Nitrobenzene being a covalent compound is insoluble in water but soluble in benzene,

alcohol etc.

9. The correct order of magnitude of bond angles among the compounds and

is

(A) (B)

(C) (D)

Solution: (B)

Bond angles depend upon number of lone pair (s) of electrons. Higher the number of

lone pairs of electrons, lesser the bond angle.

10. Which one of the following reactions does not form gaseous product?

(A)

(B) Acidified

(C)

(D)

Solution: (C)

Hydrogen peroxide oxidise lead sulphide into lead sulphate which is a solid.

11. Observe the following reaction

The rate of formation of C is What is the value of

[ ]

( )

(A) (B)

(C) (D)

Solution: (C)

Rate of reaction,

[ ]

[ ]

[ ]

[ ]

[ ]

12. Which one of the following is employed as antihistamine?

(A) Diphenyl hydramine

(B) Norethindrone

(C) Omeprazole

(D) Chloramphenicol

Solution: (A)

Diphenyl hydramine (Benadryl) is used as an antihistamine.

13. If is amount of adsorbate and is amount of adsorbent, which of the following

relations is not related to adsorption process?

(A)

( ) at constant p

(B) ( ) at constant (

)

(C)

(D)

( ) constant T

Solution: (C)

is the incorrect relation. The correct relation is

14. Standard electrode potential of three metals and are and

respectively. The reducing power of these metals will be

(A) (B)

(C) (D)

Solution: (B)

Higher the reduction potential, lesser the reducing power.

Order of reducing power is

15. Which of the following compounds has the lowest melting point?

(A) (B) (C) (D)

Solution: (B)

As covalent character increases, melting point decreases, thus order of melting point is

16. The dissociation equilibrium of a gas can be represented as

( ) ( ) ( )

The degree of dissociation is and is small compared to 1. The expression relating the

degree of dissociation ( ) with equilibrium constant and total pressure p is

(A) (

) (B) (

)

(C) (

)

(D) (

)

Solution: (B)

( ) ( )

( ) ( )

Where, degree of dissociation

Total moles at equilibrium

( )

So, ( )

( )

( )

( )

( )

( )

( )

( )

(

)

( ( )( )

)

( ) ( )

[ ( ) ( ) ]

(

)

17. A buffer solution is prepared in which the concentration of is 0.30 M and the

concentration of is 0.20 M. If the equilibrium constant, for equals

, what is the pH of the solution?

(log 2.7 = 0.43)

(A) 9.43 (B) 11.72 (C) 8.73 (D) 9.08

Solution: (A)

[ ]

[ ]

[ ]

[ ]

( )

18. If a gas expands at constant temperature indicates that

(A) Kinetic energy of molecules decreases

(B) Pressure of the gas increases

(C) Kinetic energy of molecules remains as same

(D) Number of the molecules of gas increase

Solution: (C)

Here, the temperature of gas remains constant hence kinetic energy of molecules

remains the same.

19. If the correct sequence for filling of electrons will be

(A) ( ) ( )

(B) ( ) ( )

(C) ( ) ( )

(D) ( ) ( )

Solution: (D)

For electron are filled as

This is because electrons first enters in that orbitals for which ( ) is lower. In case, if

( ) is same, it goes first in that orbital for which is lower.

20. Which of the following is least likely to behave as Lewis base?

(A) (B) (C) (D)

Solution: (B)

is an electron deficient species, thus behaves like as Lewis acid.

21. In DNA, the complimentary bases are

(A) Adenine and thymine; guanine and cytosine

(B) Adenine and thymine; guanine and uracil

(C) Adenine and guanine, thymine and cytosine

(D) Uracil and adenine; cytosine and guanine

Solution: (A)

Deoxyribonucleic acid (DNA) has the purine bases adenine and guanine and pyrimidine

bases thymine and uracil. According to base pairing rule adenine paired with thymine

( ) and cytosine paired with guanine ( ).

22. Which of the following is not a resonating form of benzaldehyde?

(A)

(B)

(C)

(D)

Solution: (B)

The structure in which, more electronegative atom carries positive charge and

electropositive atom carries negative charge highly unstable or in other words such

structure is not possible.

23. Which one of the following does not undergo iodoform reaction?

(A) Secondary butyl alcohol

(B) <i>Iso</i>-propyl alcohol

(C) Diethyl ketone

(D) Ethyl alcohol

Solution: (C)

(i)

(ii)

(iii)

(iv)

24. Percentage of free space in a body centre cubic unit cell is

(A) 30% (B) 32% (C) 34% (D) 28%

Solution: (B)

Packing fraction

For body centred cube,

Packing fraction

(

√ )

√

Volume occupied = 68%

and volume vacant = 32%

25. For the reaction, ( ) ( ) ( ) the equilibrium constant is . The

equilibrium constant is for the reaction, ( ) ( ) ( ). What is for

the reaction, ( )

( ) ( )?

(A)

( ) (B) *

+

(C)

( ) (D)

( )

Solution: (B)

( ) ( ) ( ) …..(i)

( ) ( ) ( ) …….(ii)

( ) ( ) ( )

For ( )

( ) ( ) *

+

26. Acidified solution turns green when is added to it. This is due to

the formation of

(A) (B) ( )

(C) (D) ( )

Solution: (D)

( )

27. Among the following the least thermally stable is

(A) (B) (C) (D)

Solution: (D)

Thermal stability

Of carbonates increases on moving down a group. Thus, lithium carbonate. is

least thermally stable.

28. Which one of the following is ‘d’-block element?

(A) Gd (B) Hs (C) Es (D) Cs

Solution: (B)

The element in which last electron enters in d-orbital is called d-block element. The

electronic configuration of the given elements are as follows

( ) [ ]

( ) [ ]

( ) [ ]

( ) [ ]

Thus, Hs is a d-block elements.

29. The angular shape of ozone molecule ( ) consists of

(A) 1 sigma and 2 pi bonds (B) 2 sigma and 2 pi bonds

(C) 1 sigma and 1 pi bonds (D) 2 sigma and 1 pi bonds

Solution: (D)

Single bond contains bonds

Double bond contains bonds bonds

Triple bond contains bonds bonds

The molecule of is bent with an angle and equal distance of 128 pm.

The ozone molecule consists of 2 sigma and 1 pi bonds. The angular shape of molecule

is represented as

30. If the for a given reaction has a negative value then which of the following gives

the correct relationships for the values of and ?

(A) (B)

(C) (D)

Solution: (C)

When is negative, then

in one, i.e.,

31. Among the following the molecule possessing highest dipole moments is

(A) (B) (C) (D) Trans – 2-butene

Solution: (C)

Among the given compounds-molecules, only has unsymmetrical (angular)

structure, thus has the highest dipole moment.

32. An electron is moving in Bohr’s fourth orbit. Its de-Broglie wave length is . What is

the circumference of the fourth orbit?

(A)

(B) (C) (D)

Solution: (C)

According to Bohr’s concept, an electron always move in the orbit with angular

momentum (mvr) equal to

.

Or

(

)

Or

(from de-Broglie equation,

)

For fourth orbit ( )

Circumference

33. The standard enthalpies of formation of ( ) ( ) ( ) and ( ) are –

46.19, - 393.4, +24.94 and -296.9 kJ respectively. The increasing order of their

stability is

(A) (B)

(C) (D)

Solution: (B)

Lower the value of standard enthalpy of formation, higher the stability. The increasing

order of standard enthalpies of formation of given molecules is

Thus, the increasing order of stability is

34. Green chemistry means such reactions which

(A) Produce colour during reactions

(B) Reduce the use and production of hazardous chemicals

(C) Are related to the depletion of ozone layer

(D) Study the reactions in plants

Solution: (B)

Green chemistry involves such reactions which reduce the use and production of

hazardous or toxic chemical to reduce pollution from environment.

35. Which of the following compounds gives carbylamines test?

(A) N-methyl-o-methyl aniline

(B) N, N-dimethyl aniline

(C) 2 4-dethyl aniline

(D) p-methy-N-methyl benzylamine

Solution: (C)

Carbylamine reaction is given by only primary amines

Hence, 2, 4-dimethylaniline gives carbylamines test.

36. Which of the following is an example for heterogeneous catalysis reaction?

(A) ( ) ( ) ( )→ ( )

(B) Hydrolysis of aqueous sucrose solution in the presence of a aqueous mineral acid

(C) ( ) ( )→ ( ) ( )

(D) Hydrolysis of liquid in the presence of aqueous mineral acid

Solution: (C)

( ) ( )→ ( ) ( )

In this reaction, reactant and catalyst are in different phase, hence it is an example of

heterogeneous catalysis.

37. Which of the following pair of metals is purified by van – Arkel method?

(A) Zr and Ti (B) Ag and Au (C) Ni and Fe (D) Ga and

ln

Solution: (A)

Zr and Ti are purified by van-Arkel method.

38. Name the type of the structure of silicate in which one oxygen atom of [ ] is

shared?

(A) Sheet silicate

(B) Pyrosilicate

(C) Three dimensional silicate

(D) Linear chain silicate

Solution: (B)

In pyrosilicate, only one oxygen atom is shared.

39. In Fischer – Ringe’s method of separation of nobles gas mixture from air,…… is

used

(A)

(B) Coconut charcoal

(C) Soda lime + potash solution

(D)

Solution: (A)

In Fischer Ringe’s method, air free from moisture and is passed over a heated

mixture ( ) of 90% in an iron tube, when following reactions

take place

→

gas is now absorbed by solution. Thus a mixture of inert gases is obtained.

40. Which one of the following is present as an active ingredient in bleaching power for

bleaching action?

(A) ( ) (B) (C) (D)

Solution: (A)

( ) , calcium hypochlorite is the active ingredient in bleaching power which

releases chlorine.