jms-2 paper -1 - solutions

8/2/2019 Jms-2 Paper -1 - Solutions

1/12


2/12

JMS 2 PAPER 1

http://www.chemistrycrest.com/ Page 2

SECTION I (Total Marks : 21)(Single Correct Answer Type)

This section contains 7 multiple choice questions. Each question has four choices (A), (B), (C) and (D) out ofwhich ONLY ONE is correct.

1. For the reaction A+B 2C, equal moles of A and B are placed in a container at 250C. At

equilibriium, it is found that concentration ratio of [C] to [A] is equal to 2, then value of G0 isequal to(A) 826.29 cal (B) -693.2 cal(C) 277.28 J (D) 596 J

Sol : (A)A+B 2C

Initially, [ ] [ ]A B=

At equilibrium,[ ]

[ ][ ]2; 2

CC A

A= =

[ ]

[ ] [ ]

2 22 44

2A A

KA B A

= = =

0 2.303 logG RT K =

2.303 2 298 log 4= 826.29 cal=

2. Match the following.

Column-I Column-II

(a)XeF +H O

4 2Complete

hydrolysis

(P) HF

(b)XeF +H O

6 2Complete

hydrolysis

(Q) XeO3

(c) (R) SiF4

(d) (S) XeO F2 2

A) a - R ,S; b - P,S; c - Q; d -P,RB) a- P; b R , S; c Q ,S; d Q ,PC) a- P,Q; b - P,Q; c P ,S; d - R,SD) a - S; b - P,R; c Q , R; d -P


3/12

JMS 2 PAPER 1


Sol. (C)

Complete Hydrolysis6 12 4 2 24 3

4 2 3 2 XeF H O Xe XeO HF O+ + + +

Complete Hydrolysis3 6

6 2 3 XeF H O XeO HF + +

Partial Hydrolysis2

4 2 2 2 XeOF H O XeO F HF + +

2 24 2 2 2 4

XeOF SiO XeO F SiF + +

3. An organic compound (X) with molecular formula C7H

8O is insoluble in aq NaHCO

3but dissolves

in NaOH. When treated with Bromine water, X rapidly gives Y, C7H

5OBr

3. The compounds

X and Y respectively are

(A) Benzyl alcohol and 2,4,6 Tribromo 3methoxy phenol(B) o-Cresol and 3,4,5 Tribromo 2 methyl phenol(C) m Cresol and 2,4,6 tribromo 3 methyl phenol(D) Benzyl alcohol and 2,4,6 tribromo 3 methyl phenol

Sol. (C)Compound X(C7H8O) must be a phenolic compound since it is soluble in NaOH and insoluble in

NaHCO3.X on treatment with Br2 water is giving Y with three Br atoms.(C7H5OBr3)So, placement of OH and CH3 must be such that they reinforce each other in electrophilic substitution

Therfore, it must be m Cresol.-OH is more activating than -CH3. So, all the o- and para positions wrt OH are substituted.

OH

CH3

(X)

Br2

H O2

Br

Br

Br

CH3

OH

(Y)m - cresol

4. The oxidative cleavage of Glucose (A) and Fructose (B) with 4HIO leads to the formation of acids,aldehydes and also CO2. The ratio of no of moles of formic acid to formaldehyde formed in case of(A) and (B) are respectively

a) 5:1 , 3:2 b) 5:2 , 3:1 c) 3:2 , 5:2 d) 4:2 , 5:1

Sol. (A)


4/12

JMS 2 PAPER 1


5.

( )

( )

1 NaOI A B

+2 H

O

.Starting compound A is

A)

O

CH C OH2

O

(B)

C OH

O

O (C)

C CH3

O

O (D)

C CH3

O

O

Sol. (C)


5/12

JMS 2 PAPER 1


6. An alkali metal hydride (NaH) reacts with diborane in Y to give a tetrahedral compound Z whichis extensively used as reducing agent in organic synthesis. Y and Z in the above reaction are(A) C2H6, C2H5Na (B) C2H5OC2H5, NaBH4(C) NH3, B3N3H6 (D) C3H8, C3H7Na

Sol. (B)

( )

( ) ( )

22 52 22 6 4

C H O

NaH B H NaBH

ZY

+

4BH

is tetrahedral. (As per VSEPR, it has 4 bonded and 0 lone pairs)

7. The following canonical structures follow the stability order

+

= NN

= NN

NN

I II III (A) I > II > III (B) III > I > II(C) II > III > I (D) II > I > III

Sol. (D)

SECTION II (Total Marks : 16)(Multiple Correct Answers Type)

This section contains 4 multiple choice questions. Each question has four choices (A), (B), (C) and (D) out ofwhich ONE OR MORE may be correct.

8. Which of the following is/arecorrect for the characteristics indicated against each(A) NH3 > PH3 > AsH3 > SbH3 (boiling point)(B) BF3 < BCl3 < BBr3 < BI3 (lewis acid strength)(C) H3PO2 > H3PO3 > H3PO4 (acidic strength)(D) HClO < HClO2 > HClO3 < HClO4 (acidic strength)

Sol. (B,C,D)Boling points order of hydrides of V A group elements is BiH3 > SbH3 > NH3 > AsH3 > PH3


6/12

JMS 2 PAPER 1


9. Which of the following statement(s) is/arecorrect(A) Cuprite and Zincite are oxide ores(B) Magnesite and carnallite are carbonate ores(C) Chalcocite and azurite are ores of copper(D) Felspar and mica contain aluminium.

Sol. (A,C,D)

Cuprite and zincite are Cu2O and ZnO.Magnesite and carnallite are MgCO3 and KCl MgCl2 6H2OChalcocite and azurite are Cu2S and 2CuCO3 . Cu ( OH)2Felspar and mica are KAlSi3O8 and K2O 3Al2O3 6SiO2 2H2O

10. Which of the following is/are correct order with respect to the property mentioned.(A) O22 > O2 > O22+ [Paramagnetic moment]

(B) (NO) > (NO) > (NO)+ [bond length](C) H2 > H2+ > He2+ [bond energy]

(D) NO2+ > NO2 > NO2 [bond angle]

Sol. (B,C,D)

Correct paramagnetic moment is O2 > O22+ = O22Acc to MOT, O2 has 2 unpaired e

- and the remaining two have 0 unpaired e-s each

11. Which of the following statement(s) is /arecorrect ?

(A)1

Ionisation energyscreening effect

(B) The ionisation energies of Be and Mg are more than ionisation energy of B and Al respectively.(C) Atomic and ionic raddii of Nb and Ta are almost same(D) Metallic and covalent radii of potassium are 2.3 and 2.03 respectively.

Sol. (A,B,C,D)

(A) As Screening effect increases, effective nuclear charge decreases, thus valence shell electron isloosely bound. Hence I.E decreases.(B) Be and Mg have ns2 configuration (stable configuration)(C) It is due to lanthanide contraction(D) rmetallic > rcovalent (covalent bond formation involves the overlapping of orbitals)


7/12

JMS 2 PAPER 1


SECTION-III (Total Marls : 15)(Paragraph Type)

This section contains 2 paragraphs. Based upon one of paragraphs 2 multiple choice questions andbased on the other paragraph 3 multiple choice questions have to be answered. Each of these questionshas four choices (A), (B), (C) and (D) out ofwhich ONLY ONE is correct.

Paragraph for Question Nos. 12 and 13

Aqueous solution of A White precipitate soluble in excess of NaOH BH SO

2 4

H O

2 2

White precipitate soluble in Brown precipitate Cammonium acetate D

.Further,

aqueous solution of A white precipitate soluble in NH3.

K Cr O2 2 7

HCl / H S

2

Yellow ppt

Black ppt insoluble in NaOH

12. The complex B , which is soluble in excess of NaOH is(A) Na[Cu(OH)4] (B) Na2[Pb(OH)4](C) Bi(OH)3 (D) Na2SnO2

Sol. (B)

( )

( )PbCl 2 NaOH Pb OH 2 NaCl22whiteA

+ +

( ) ( )

( )2 4

Pb OH 2NaOH Na Pb OH2 B

+

13. Aqueous solution of A on treatment with HCl / H2S gives a black ppt. Thus which of the cationic

species must not be present in compound A.

(A) Hg2+ B) Pb+2 C) Cd2+ D) Bi3+

Sol. (C)HgS, PbS and Bi2S3 are black in color whereas CdS is yellow.


8/12

JMS 2 PAPER 1


Paragraph for Question Nos. 14 to 16

Benzoic aicd, phenol, toluene and aniline were dissolved in dichloromethane . The solution was thentreated with 10% aq.HCl. After that, aqueous layer was collected in container I. Oily layer was furthertreated with 10% aq NaOH. This time aqueous layer was collected in container II and oily layer wascollected in container III.

14. Container I contains

(A) (B)

OH

(C) Both A and B (D)

NH2

Sol. (D)15. Compound present in container II is

(A)

COOH

(B)

OH

(C) Both A and B (D)

NH2

Sol. (C)

16. Compound present in container III is

(A)

NH2

(B)

COOH

(C)

OH

(D)

CH3

Sol. (D)


9/12

JMS 2 PAPER 1


Solutions for Q. No 14 , 15 and 16.

SECTION-IV (Total Marks : 28)

(Integer Answer Type)

This section contains 7 questions. The answer to each of the questions is a single digit integer, rangingfrom 0 to 9. The bubble corresponding to the correct is to be darkened in the ORS.

17. Among the following the total number of species which give two more than two types of acids onaddition of water is

NO2 , N2O, ClO2, NO, Cl2O6, P4O6, P4O10, Cl2.Sol : (4)


10/12

JMS 2 PAPER 1


2 2 2 32 NO H O HNO HNO+ +

2 2 2 32ClO H O HClO HClO+ +

3 2 3 42ClO H O HClO HClO+ + 2 2Cl H O HCl HClO+ +

18. 20% surface sites are occupied by N2 molecules. Number of surface sites per unit area is

6.023 1014 cm2 and total area of catalyst surface is 1000 cm2 . When catalyst is heated to 300K

N2 gas is desorbed and evolved gas occupied, 2.46 cm3 at 0.001 atm. Find the no. of sites ocupied

by each molecule of N2.

Sol : (2)

Total no. of surface sites = 1000 6.023 1014 = 6.023 1017

Total no. of sites occupied = 0.2 6.023 1017 = 2 6.023 1016

No of moles of nitrogen desorbed = n =30.001 2.46 10

0.082 300x x

x

So, no. of nitrogen molecules =62.46 10

24.6x

6.023 1023 = 6.023 1016

no. of sites per molecule of N2 =16

16

2 6.023 106.023 10x x

x

= 2.

19. Total number of structural and stereoisomers obtained from monochlorination of methylcyclohexane is

Sol : (7)

CH Cl2

CH3

Cl

CH3

Cl

Cl

CH3

Cl

CH3

(achiral) (achiral) chiral chiral (achiral)(a pair) (a pair)


11/12

JMS 2 PAPER 1


20. In case of [Cu(NH3)

4]

2+, 4p subshell contains ----------- unpaired e

-

Sol. (1)

`

[Cu(NH3)

4]

2+

NH 3 is a strong field ligand.

21. 10 g of mixture of hexane and ethanol are allowed to react with sodium to give 214.2 mL hydrogen

at 270C and 760 mm pressure. The percentage of ethanol in the mixture is

Sol. (8)The given mixture (hexane + ethanol) weighs 10 g.The mixture reacts with Na to give 214.2 mL hydrogen at 27 0C and 760 mm pressure.Only ethanol liberates hydrogen upon reaction with Na and thus,

2 5 2 5 21/ 2C H OH Na C H O Na H ++ + No. of moles of H2 formed

31 214.2 8.69 101000 0.0821 300

PV

RT

= = =

moles

1/2 mole of H2 is formed from 46 g of ethanol38.69 10 moles are formed from

346 8.69 100.8

1/ 2

= g of C2H5OH.

of ethanol in mixture =

0.8 100

8%10

=

22 The number of OH groups in the product obtained by reacting 3-methylbutane-1, 3-diol withTsCl followed by NaBH4 is

Sol. (1)

CH3

TsClCH C CH CH OH

3 2 2

OH


12/12

JMS 2 PAPER 1


CH3

4CH C CH CH OTs3 2 2BH

OH

CH3

CH C CH CH3 2 3

OH

Sterically hindered OH group does not react with TsCl.

23. A small piece of white phosphorus was reacted with excess Cl2 gas to yield 68.75 grams of

phosphorus trichloride. No of discrete 4P molecules in the sample is (X.Y x 1022) . X is

Sol: (7)

4 2 3

6 4P Cl PCl+

3 3 4

68.75 1 1 1137.5 2 4 2

mole PCl mole PCl moles P= =

Number of 4P molecules =23 231 6.023 10 0.75 10

8 =

jms-2 paper -1 - solutions

Documents