Maximum Marks: 40

Question paper format and Marking scheme:

1. This question paper has 40 questions of equal weight age. Each question is allotted 1 mark for each correct response.

2. No deduction from the total score will be made if no response is indicated for an item in the answer sheet.

CHEMISTRY CRESTEAMCET 2008(MEDICINE)3. There is only one correct response for each question. Filling up more than one response in each question will be treated as wrong response

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121. The wavelength

in A0

of an emission line obtained for Li2+ during an electronic transition from

n2 2 to n1

1 (R = Rydberg constant)(1) 3R (2) 27 R (3) 4

(4) 4 4 4 3R

27 R

Sol. (4) = R .Z2 1 1 H n 2

n 2

1 2

For

Li2

, v R.32 1 1

27 R12 22 4 427 R

122. Match the following:

List IList II (at STP)

(A)nh mvr2(i)Paschen series

(B)Infra-red(ii)Electron total energy

(C)h / p(iii)De Broglie equation

(D)e2 / 2r(iv)Schodinger equation

(v)Bohrs equation

The correct answer isABCD

(1)viiiiii

(2)iiiiiviv

(3)viiiiii

(4)iviiiiii

Sol. (3)

(A) mvr

nh -Bohrs equation2(B) Infrared paschen series(C) h p

de-Broglies equation(D)

e2 / 2r - Total energy of electron

123.A particle B particle C pa In the conversion, which one of the following i (1) A and D are isotoperticle Ds not true?(2) B and C are isodiaphers

(3) C and D are isobars(4) A and B are isotopes

Sol.(4)A and B are isobars but not isotopes.

When a particle is emitted, isobar is formed

When particle is emitted, isodiapher is formedWhen 1 and particles are emitted, isotope is formed

124. The elements X, Y and Z form oxides which are acidic, basic and amphoteric respectively.The correct order of their electro-negativity is(1) x > y > z (2) z > y > x(3) x > z > y (4) y > x > z

Sol. (3)X forms acidic oxide. E.N of X is highY forms basic oxide E.N of Y is lowZ forms amphoteric oxide. Moderate E.N.Order of E.N. X > Z > Y

125. Match the following:

BC 3

List IList II(A)l(i)Linear(B)PdBr 24(ii)Planar Triangular(C)F(iii)Tetrahedral(D)I3(iv)Octahedral(v)Square planarS 6

The correct answer isABCD

(1)iiiiiivi

(2)viiiiii

(3)iivivi

(4)viviiiii

Sol. (3)

(A) BCl3 Planar triangular (B)

PdBr 24

-square planar

(C) SF6 Octahedral (D) I3

-linear

126. The correct order of dipole moments for NH3, H2O and CO2 molecules isO NH H OO (2) C

2 3 2O

Sol. (4)

O NH (4)

H2O NH3 C 2H2O has dipole moment = 1.84 D NH3 has dipole moment = 1.46 D CO2has dipole moment = 0 DOThe correct order is

H2O NH3 C 2

127. 40 grams of a sample of carbon on combustion left 10% of it unreacted. The volume of oxygen required at STP for this combustion reaction is(1) 22.4 I (2) 67.2 I (3) 11.2 I (4) 44.8 I

Sol. (2)Unreacted carbon = 40 10 4 g.100Carbon burnt = 40-4 = 36 g. = 3 moles

C + O2

CO23 moles 3 22.4= 67.2 lit at STP.

128. In a flask of V litres, 0.2 moles of O2, 0.4 moles of N2, 0.1 moles of NH3 and 0.3 moles of He gases are present at 27 0C. If total pressure exerted by these non-reacting gases is 1 atm, the partial pressure exerted by N2 gas is(1) 0.4 atm (2) 0.3 atm (3) 0.2 atm (4) 0.1 atm

Sol. (1)Total no. of moles = 0.2 + 0.4 + 0.1 + 0.3 = 1Moles fraction of N2 = 0.4Partial pressure = Mole fraction x Total pressureP 0.4 1 0.4N2

Atm.129. The volumes of two HCl solutions A 0.5N and B(0.1N) to be mixed for preparing 2l of 0.2M HClsolution(1) 0.5 l of A + 1.5 l of B (2) 1.5 l of A + 0.5 l of B(3) 1 l of A + 1 l of B (4) 0.75 l of A + 1.25 l of B

Sol. (1)

Conc. of final solution =

0.25 0.15 0.4 0.2 N2 2

0.5 0.5 1.5 0.12

130. When 0.1 moles of an acid is added to 2 litres of a buffer solution, the pH of the buffer decreases by 0.5. The buffer capacity of the solution is(1) 0.6 (2) 0.4 (3) 0.2 (4) 0.1

Sol. (4)Buffer capacity = No. of moles of acid or base added to 1 lit. of the solutionChange in pH= 0.050.5

0.1

131. Identify Bronsted-Lowry acids in the reaction given 3 2 O

Al H O

OH H CO

2Al H O 6 A

HC 3B

2 2 3 5 DCThe correct answer is(1) (A), (C) (2) (B), (D)(3) (A), (D) (4) (B), (C)

Sol. (3)3 H 2 O Al H O OH Al H 2 6 2 5Acid

HCO

H H CO3 2 3Acid

132. The cell potential of the following cell at 250 C (in volts) isH+ Cu 2+ 0

EPt H2 0.01M 0.1M Cu1atm

Cu2+ / Cu

0.337V (1) 0.308 (2) 0.427 (3) 0.308 (4) 0.337

Sol. (2)Net reaction : H2 + Cu 2+ 2H+ + CuE E 0 0.059 log [ pds]n [rea]0.06 (0.01)2E (0.337 0.00) log2 (0.1)E 0.337 0.03(3)E 0.427V

133. Which one of the following reactions occur at the cathode?

(1) 2OH H 2O

1 / 2 O2

2e (2)

Ag Ag1 e

(3)

Fe2

Fe3

e (4) Cu2 2e Cu

Sol. (4)Reduction occurs at cathode. Gain of electrons is reduction.

134. AB is an ionic solid. If the ratio of ionic radii of A+ and B- is 0.52. What is the coordination number of B ?(1) 2 (2) 3 (3) 6 (4) 8

Sol. (3)

If the Limiting radius ratio r r

0.414 0.732 , then coordination no. is 6.135. The rate constant of a first order reaction is 0.0693 min 1 . What is the time (in minutes) required for reducing an initial concentration of 20 mol 1 to 2.5 mol 1 ?(1) 40 (2) 30 (3) 20 (4) 10

Sol. (2)First order rate constant expression,K 2.303 log a t

0.0693

(a x)2.303 log 20t 2.5t log 8 3 log 20.0301 0.03013x0.301 300.0301

136. A Bg g

is a first order reaction. The initial concentration of A is 0.2 mol 1 l 1 . After 10minutes, the concentration of B is found to be 0.18 mol 1 l 1 . The rate constant (in min 1 ) for the reaction is(1) 0.2303 (2) 2.303 (3) 0.693 (4) 0.01

Sol. (1)

K

2.303 log 0.2 t 0.2 0.182.303 log10 0.2303 min 1t

137. 100 cm3 of 0.1M HCl and 100 cm3, a 0.1 M NaOH solutions are mixed in a calorimeter. If the heatliberate is Q kcal, the heat of neutralization H (in Kcal) of HClaq

and NaOH isaq(1) 10 Q (2) -100 Q (3) -1000 Q (4) Q

Sol. (2)No. of moles of HCl and NaO H = 100 0.1 = 0.01 moles10000.01 mole reacts with 0.01 moles to liberate ----------- Q kcal1 mole reacts with 1 mole to liberate ..?=100 Q kcalTherefore , heat of neutralization = - 100 Q

138. Which one of the following reactions is an example of auto-catalysis?

(1) 2 AsH3 s

2 As s

3H 2 g

(2) N2 g

3H 2 s

Fe s

NO g

2 NH3 g(3) 2SO O2 g 2 g

2SO3 g

H lC H O H O C H O C H O(4) 12 22

11 l 2 l

6 22 6 l

6 12 6 l

Sol. (1)As is auto-catalyst in the decomposition of AsH32 AsH3 s

2 As s

3H 2 g

139. If 11.1 mg of CaCl2 and 12 mg of MgSO4 are present in 2 litres of water, what is its hardness (in grams CaCO3/ppm)?(1) 5 (2) 10 (3) 15 (4) 20

Sol. (2)11.1 mg MgCl2 = 10 mg CaCO312 mg. MgSO4 = 10 mg CaCO311.1 mg MgCl2 + 12 mg. MgSO4 = 20 mg. CaCO32000g. of water contain 20 g. of CaCO31000106 g. of water contain? Degree of hardness of water =

20 1061000 2000

10 ppm.

140. The correct order of stability for the following superoxides is(1) KO2

RbO2

CsO2

(2)

RbO2

CsO KO2 2(3) CsO2

RbO KO2 2

(4) KO2

CsO2

RbO2

Sol. (3)As the size of the alkali metal ion increases, the stability of the superxoide increases due to the increasein lattice energy.The correct order is CsO2

RbO KO2 2

141. A mixture of boron trichloride and hydrogen is subjected to silent electric discharge to form Aand HCl. A is mixed with NH3 and heated to 200 0C to form B. The formula of B is(1) H3BO3 (2) B2O3 (3) B3N3H6 (4) B2H6

Sol. (3)

2BCl 6H

silent electric discharge B H

6HCl3 2 2 61200 C

2000 CB H NH B H NH B N H2 6 2

3 2 6.2

3 3 3 6

142. Hydrolysis of SiCl4 gives compound X and HCl. On heating to 1000 0C X loses water and forms Y.Identify X and Y, respectively(1) SiO2 and Si (2) H4SiO4 and SiO2 (3) SiO2 and SiC (4) H4SiO4 and SiC

Sol. (2)

l H O H SiO HClSiC 4

4 2 4 4 4Orthosilicic acid1000 0CO SiO H OH 4Si 4 2 2 2

143. The number of P-O bonds and lose pairs of electrons present in P4O6 molecule, respectively(1) 12, 16 (2) 12, 12 (3) 8, 8 (4) 12, 4

Sol. (1)

No. of P O bonds = 12No. of lone pairs of electrons = 16

144. X, Y are anhydrides of sulphurous acid and Sulphuric acid, respectively. The hybridization state and the shape of X and Y areX Y(1) sp2 , angular (2) sp2 , angular (3) sp2 , angular(4) sp3 , planar

sp3 , tetrahedralsp2 , angularsp2 , planar triangularsp3 , planar

Sol. (3)Anhydride of sulphurous acid, H2SO3 (X) is SO2. Hybridization of S in X is sp2. Shape angular. Anhydride of Sulphuric acid, H2SO4 (Y) is SO3. Hybridization of S in Y is sp2. Shape is plane triangular.

145.

Ca OH 2dry

Cl2H 2O

A auto-oxidation

CaCl B2Identify B in the above reaction.

l O(1) CaOC 2

(3) Ca OH 2

(2) Ca Cl 3 2(4) Ca CI 2 2O

Sol. (2)

Ca OH 2

Cl2

2CaOCl H O2dry A

l Ca ClO6Ca OCl Cl

5CaC 2 3 2B

146. Which of the following statements about Noble gases are correct?I. XeO3 is an explosive tetrahedral molecule.II In Fisher Ringe Method, a mixture of CaCl2 and CaC2 is used to remove N2 and O2.III. He and Ne are chemically inert due to lack of d-orbitals and high ionization potential.IV. At 173 K He and Ne are absorbed on activated charcoal. The correct answer is(1) I and II (2) II and III(3) II, III and IV (4) I, II, III and IV

Sol. (2)II and III are correct statements. I and IV are wrong statements.

147. Which one of the following pairs of complexes has the effective atomic number equal to 36 for the transition element?

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l

Cr H O

Cl

(1) Co NH 3 6

C 3; K3 Fe CN 6

(2) Co NH3 6

C 3;

2 6 3(3) Fe CO 5 ; K 4 Fe CN 6

(4) Fe CO

; K

Fe CN

5 3 6

Sol. (3)EAN = Z oxidation state of metal + 2 x C. No

Fe CO 5 ; EAN = 26 0 + 2x5 = 36

6K4 Fe CN

; EAN= 26 2 + 2 x 6= 36

148. 5 l aqueous solution is kept in the presence of oxygen and suitable micro-organism for five days at2000 C . If the O2 consumed is 0.2 g. the BOD value of the sample is(1) 4 ppm (2) 0.4 mg l 1

(3) 40 ppm (4) 20 mg l 1

Sol. (3)

BOD

No. of mg. of O2 required No. of litres of water sampleBOD = 200 40 ppm.5

149. Which one of the following graphs represent the correct order of boiling points (B.P) of ethane(I), ethyl alcohol (2) and acetic acid (3)?

(1)

Sol. (3)Ethane has no H bonds. Ther remaining two have hydrogen bonds. Possibility of H bonding is more inacetic acid(1) ethane gas lowest B.P.(2) ethyl alcohol B.P. 78.10 C (3) Acetic acid B.P. 1180 C

150. Which one of the following reactions yields 2E-butane as the major product?(1) CH3

C C CH3

Na / NH3

liq.(2) CH3

CH CH CH3

Li / NH3

liq.(3) CH3

C C CH3

Na / NH4OH(4) CH3

C C CH3

Pd / BaS 4O

Sol. (1)

151. Identify C in the following reaction:

C H Chromic acid2 2

A NH3 B C H O2(1) CH3

(3) CH3

CH 2

CH 2

NH 2

NH CH3

(2) CH3

(4) CH3

CN

OC NH 2

Sol. (4)

HC CH O H O

Chromic acid

CH COOH2 3A

COOH NH CH COONH CH CONHCH3 3 3 4 H O 3 22 C

152. C H OH SOCl2 5 2

Pyridine

X Y Z , in this reaction X, Y and Z respectively, arel O C H Cl SO HCl(1) C2 H 4C 2 , S

2 , HCl (2)

2 5 , 2 ,C H Cl SOCl HCl (4) C H

, SO

, Cl(3)

2 5 , ,

2 4 2 2

Sol. (2)

C H OH SOCl C H Cl SO HCl2 5 2 2 5 2 ZX Y

153. The compound that reacts with CH3MgBr to yield methane as one of the products is(1) CH3CHO(2) CH3COCH3

Sol.(3) CH3COOCH3

(4)(4) CH3CH2OH

C H OH CH MgBr2 5 3CH M4g OC H2 5

154. The organic compound which gives peroxy compound on exposure to atmospheric air in the presence of sunlight isC H OC H (2) CHCl(1) 2 5 2 5 3(3) CH3

H 2OH (4) CH3 HOC C

Sol. (1)

C2 H5

O C2 H5 O

C H O C H2 5 2 5

O

155. When 1, 1-dichloro propane and 2, 2-dichloro propane are reacted separately with aqueous potassium hydroxide solution, compounds A and B are formed. Both A and B gave the same product C on reduction using amalgamated zinc and HCl. Idenfity C(1) Propyl alcohol (2) Isopropyl alcohol(3) Propyl chloride (4) Propane

Sol. (4)

CH CH CHCl

KOH

CH CH CH OH CH CH CHO3 2 2 3 2

2 H O 3 22 AO

CH CCl CH

KOH

CH C OH CH CH C CH3 2 3 3

2 3 H 2O 3 3

CH C O

Zn Hg HCl

CH CH3 3 2CH3

CH CH CHO

Zn Hg HCl

CH3propane

CH CH CH3 2 3.

H+ excess Cl2

2 3Propane156.

CH CN+H O A B3 2 red PIn the above reaction, A and B are respectively(1) CH COOH, CCl COOH3 3(3) CH CHO, CCl CHO3 3

(2) CH CH OH, CH CH Cl3 2 3 2(4) CH COCH , CCl COCH3 3 3 3

Sol. (1)

CH CN H O H

CH COOH

excess Cl2

CCl COOH3 2 3A

Red P 3B

157. Nitrobenzene undergoes reduction with Zn/alcoholic KOH to form a compound A. The number ofSigma and Pi bonds in A, respectively are(1) 17, 6 (2) 27, 6 (3) 27, 8 (4) 17, 8

Sol. (2)

Nitrobenzene undergoes reduction with Zn/alcoholic KOH to form Azo Benzene. It contains 27 and 6 bonds

ON 2

2 10 H

Zn KOH alc

ON N 4H2H H

158. Which of the following compounds helps in achieving equilibrium between O2 and CO2 is atmosphere?(1) Chlorophyll (2) Vitamin-B12(3) Porphyrin (4) Acetyl salicylic acid

Sol. (1)Chlorophyll helps in maintaining O2, CO2 equilibrium in the nature.

159. Natural rubber is a polymer of

CH2

CH3CH C CH2(1) CH2

(3) CH2

CH CH CH 2 (2)CH3 CH3C C CH2 (4) CH2

CH CH2

CH3

Sol. (2)Natural rubber is a polymer of isoprene . It is cis 1, 4 - poly isoprene.CH3CH 2

CH C CH 2 isoprene

160. Match the following:

List IList II (at STP)

(A)B1(i)Riboflavin

(B)B2(ii)Pentothenic acid

(C)B3(iii)Niacin

(D)B5(iv)Thiamine

ABCD(1)iviiiiii(2)iviiiiii(3)iiiiviii(4)iviiiiiiThe correct match is

Sol.(4)

(A) B1 Thiamin(C) B3 Pentothenic acid(B) B2 Riboflavin(D) B5 Niacin