Chem 112

Universal Science College B.Sc. Biochemistry Second Term Examination - 2007 Semester: First Subject: Chem 112

F.M.: 100 Time: 3 hrs Date: 7th Feb 2007

Name: ………………………….

Roll No. ………….

1.

Which of the following has highest boiling point? a. Hexane c. 3-methyl pentane

2.

During coupling of alkyl halide with organometallic compound, the alkyl halide should be ……….

3.

For a reaction: RMgX + HOH → R – H + Mg (OH) X, HOH is a. Stronger acid b. Stronger base c. Weaker acid d. Weaker base

4.

On conversion into the Grignard reagent followed by treatment with water, how many alkyl bromides would yield n-pentane a. 1 b. 2 c. 3 d. 4

5.

What proportion of 1- chloro propane is formed on chlorination of propane? a. 60% b. 56% c. 44%

d.

40%

6.

Among methyl, ethyl, isopropyl and isobutyl radical which one is more stable? a. Methyl b. Ethyl c. Isopropyl

d.

Isobutyl

7.

Name the product formed in the following reaction: CH (CH )5 CH Br Li 3  2  2 CH3CH2Cl → CuI →   → …………….

8.

Name the enzyme which converts starch into maltose ……………..

9.

A mixture of 95% ethanol and 5% water boils at 78.150 C. The name for this constant boiling mixture is called ………………

b. d.

Isohexane 2,2 –dimethyl butane

O

10.

Give the product of the following reaction (IUPAC name) H3C

11.

Which one is stronger acid in the following reaction RONa + HOH → NaOH + ROH.

12.

The order of reactivity of alcohols toward HX is …………..

13.

Name the IUPAC name of the product in the following reaction: CH3

H3C

14. 15.

CH3 OH

+

+ C2H5 MgBr → ……..

H Cl

What is the product obtained by the dehydration of tert– butyl alcohol? Give IUPAC name ……… Arrange the following compounds in order of decreasing boiling points. a. n-hexane b. 2-methyl – 2- pentanol c. 3- hexanol d. n-octyl alcohol e. n-hexyl alcohol …………………………..

16.

Identify X, Y & Z in the following sequence of the reaction: C2H5ONa + CH3I → ×

HBr (excess ) Y + Z. 100 0 C

17.

In a nucleophilic reaction: R: W +: Z ------------→ R: Z +: W -, : W - is a. Substrate b. Nucleophile c. Leaving group d.

18.

Write the formula for the rate of a chemical reaction

19.

Write the rate order and kinetics equation for following reactions: a. CH3 Br + OH- → CH3OH+ Br – CH3

b.

H3C

CH3 Br

+

HO

-

CH3 H3C

CH3

+

Solvent

-

Br

HO

20.

A reaction that yields a product whose configuration is opposite to that of the reactant is said to proceed with ………..

21.

In ethylene each carbon is …………. hybridized.

22.

The H-C –C bond angle in ethylene is ………… degree.

23.

The

24.

The bond between C – H in ethylene is a. SP3 -S b. SP2 – S

25.

>C = C< bond distance is …………… d.

SP2 – SP2.

During dehydrohalogenation, the hydrogen is eliminated from. a. α - carbon b. β - carbon c. γ - carbon

d.

δ - carbon

26.

Dehydrohalogenation is characterised by the action of a. Acid b. Base c. Salt

d.

Oxidizing agent

27.

In dehydrohalogenation the preferred product is the alkene that has the greater number of alkyl groups attached to the doubly bonded carbon atoms. Whose rule is this? a. Markovnikov's rule b. Hoffmann rule c. Grignards rule d. Saytzeef's rule

28.

Give the order of stability of alkenes for following alkenes R2C = CR2, R2C = CHR, RCH = CHR, R2C = CH2, RCH = CH2, CH2 = CH2

29.

Give the IUPAC name for the major product formed by the dehydrohalogenation of sec-butyl bromide.

30.

Name the IUPAC name of the compound formed by the dehydrohalogenation of neo-pentyl bromide (2, 2-dimethyl – 1 bromopropane) ……….

31.

The order of reactivity of alkyl halide in E2 dehydrohalogenation is ……….

32.

The quantity of heat evolved when one mole of an unsaturated compound is hydrogenated is called the …………..

33.

In the addition of an acid to the carbon - carbon double bond of an alkene, the hydrogen of the acid attaches itself to the carbon that already holds the greater number of hydrogens. This statement is generally known as …………..

34.

Reactions that, from the stand point of orientation, give exclusively or nearly exclusively one of several possible isomeric products are called …………

c.

SP – S

35.

The phenomenon of anti Markovnikov's addition caused by the presence of peroxides in alkene is known as: a. Markovnikov's effect b. Mayo's effect c. Kharasch's effect d. Saytzeef's effect

36.

The mechanism of electrophilic addition of HX to carbon – carbon double bond is a. Free radical mechanism b. Carbocation mechanism c. Carbanion mechanism d. Carbene mechanism

37.

The mechanism of addition of HX to carbon – carbon double bond in the presence of an organic peroxide is a. Free radical mechanism b. Carbocation mechanism c. Carbanion mechanism d. Carbene mechanism

38.

During electrophilic addition to carbon – carbon double bond ……………. is necessary a. Oxidising agent b. Reducing agent c. Acidic agent d. Basic agent

39.

The addition of halogen to carbon- carbon double bond occurs by the formation of a. Carbocation b. Carbanion c. Free radical d. Halonium ion

40.

What product do you expect from the action of bromine water on 2 – methyl propene.

41.

What are X and Y in the following CH3 (CH2)3 CH = CH2

42.

NaBH 4 /OH − Hg (OCOCH 3 ) 2 X     → Y THF / H 2 O

Name A, B, C and D (BH3)2

H 2 C = CH 2

A

H 2 C = CH 2

B

H 2 C = CH 2

C

H 2 O2 / OH −

D

43.

Breaking of a covalent bond takes place by a. Homolytic fission c. Both of the above

44.

In heterolytic fission of bonds, which one of the following is produced? a. Free radicals b. Cations c. Anions d.

Both b & c

45.

Which is the correct formula of alkoxy group? a. -C2H5 b. -COOH

c.

-CHO

d.

-C2H5O

46.

Which one of the following is a nucleophile? a. H+ b. OH-

c.

CO2

d.

RH

47.

Which one of the following is an electrophile? + NO2 b. C2H5Oa.

c.

-CH3

d.

CH4

48.

Which one of the following is a Lewis acid? a. AlCl3 b. NH3

c.

Ca (OH) 2

d.

H2O2

49.

Rates of reaction depends on a. ∆F b.

c.

Both

d.

None of them

50.

Chlorination of CH4 in light takes place by a. Ionic mechanism c. Free radical mechanism

b. d.

Polar mechanism Carbonium ion mechanism

∆H

b. d.

Heterolytic fission None of the above

51.

SN2 reaction means which one of the following a. First order c. Zero order

b. d.

Second order Both first & second order

52.

Benzyne belongs to a. Free radical c. Reaction intermediate

b. d.

Stable intermediate Molecular species

53.

Aldol reaction is an example of a. Addition reaction c. Rearrangement reaction

b. d.

Substitution reaction Condensation reaction

54.

Which one of the following acts as an electrophile? c. a. R b. R+

R-

d.

R·

55.

Which one of the following is the strongest acid? a. CH3COOH b. HCOOH

C6H5COOH

d.

CH3CH2 COOH

56.

Hydrolysis of methyl bromide by alkali solution belongs to which one of the following class a. Substitution reaction b. Addition reaction c. Elimination reaction d. Rearrangement reaction

57.

The formula of Ester functional group is a. RO b. -COOR

58.

Which is the correct structure of benzene?

a.

b.

c.

c.

RCH2-

c.

d.

R–R

d.

59.

Electron sixtext is present in a. Nitrene b. Benzyne

60.

In endothermic reaction heat is a. Dissipated b.

61.

Which one of the following belong to non-kinetic method of reaction mechanism determination a. Flash photolysis b. Product formation rate analysis c. Hydrolysis rate shading d. Trapping of reactive intermediate

62.

Which one of the following is the strongest base? a. Clb. OH-

c.

CH3COO-

63.

Hoffmann hypobromide reaction illustrates a. Benzyne mechanism c. Substitution reaction mechanism

b. d.

Free radical mechanism Rearrangement mechanism

64.

Stereochemistry deals with a. Structural isomerism c. Space isomerism

b. d.

Functional group isomerism None of the above

65.

Stereomerism is shown by a. Enantiomerism c. Optical isomerism

b. d.

Geometrical isomerism All of the above

66.

Enantiomerism is the same thing as a. Optical isomerism c. Cis-trans isomerism

b. d.

Diasteriomerism Conformational isomerism

c.

Evolved

Carbanion c.

d.

Absorbed

Free radical d.

d.

None of them

RO-

67.

Geometrical isomers are a. Structural isomers c. Optical isomers

68.

How many different compounds are possible for the formula CWXYZ? a. One b. Two c. Three

69.

Polarimeter is the name of an instrument for measuring a. Reaction rate b. c. Light rotation d.

70.

The formula for calculation of specific rotation is a.

b.

c.

d.

71.

Dissymmetry means a. Lack of symmetry c. Both of them

b. d.

Presence of symmetry None of them

72.

Chiral molecule means a. symmetric molecule c. Asymmetric molecule

b. d.

Dissymmetric molecule None of the above

73.

Enantiomers have properties a. Same b.

c.

Similar d.

74.

Enantiomers are a. Superimposable c. Convertible

b. d.

Non super imposable All of the above

75.

Which one of the following conformation for butane is most stable? a. Staggered conformation b. Eclipsed conformation c. Gauche conformation d. Skewed conformation

76.

Conformational stability depends on the following a. Angle strain c. Van der waal strain

77.

Which one of the following is the most stable conformation of cyclohexane? a. Chair conformation b. Boat conformation c. Twist conformation d. Equatorially substituted chair conformation

78.

How many stereoisomers are possible for 1, 3-cyclopentane dicarboxylic acid? a. One b. Two c. Three d.

79.

Which of the following has the highest priority in sequence rule of R and S-configuration determination? a. Cl b. Br c. I d. F

80.

Racemic mixture contains a. Excess of one stereoisomer over the other b. Less of one stereoisomer than the other c. Equal amount of one stereoisomer and the other d. Only one stereoisomer

81.

Mesostereoisomer has a. Symmetry plane c. Centre of symmetry

b. d.

Different

b. d.

b. d.

Diasteriomers Conformational isomers d.

Four

Reaction mechanism Light dispersion

Dissimilar

Torsional strain All of them

No symmetry plane Axis of symmetry

Four

82.

Mesostereoisomer is a. Diastereomer c. Optical isomer

b. d.

Enantiomer Geometric isomer.

83.

Cyclohexane chain conformation has a. All axial bonds c. 6 axial and 6 equitorial bonds

b. d.

All equatorial bonds None of the above

84.

Which one of the following obeys Bayer strain theory? a. Cyclopropane b. c. Cyclodecapentane d.

85.

Which one of the following has the biggest angle strain? a. ∆ b. c.

86.

L- lactic acid is a. Dextrorotatory c. Nonrotatory

87.

Which one of the following belongs to Z System?

a.

Cl

H

Cl

CH3

b. d.

b.

Cl

H

H3C

Cl

Cyclohexane Large cyclic compounds d. Laevorotatory Disrotatory

Cl

c.

H

CH3

b. d.

cis-trans isomers Conformational isomers

88.

Maleic and fumaric acids are examples of a. Optical isomers c. Structural isomers

89.

Glucose can exists in how many stereoisomeric configurations a. 2 b. 4 c. 8

90.

Conformational isomers are a. Rotational isomers c. Geometric isomers

91.

The properties of diastereomers are the same as that of a. Enantiomers b. c. Mesoisomers d.

b. d.

***

Br

Cl

d.

d.

H

16

Configurational isomers Structural isomers Geometric isomers None of them

Cl

Cl