chemistry jee main

8/11/2019 Chemistry Jee Main

1/15

CHEMISTRY

1.Number of waves made by an electron in one complete revolution in 3rdBohr orbit is(A) 2 (B) 3(C) 4 (D) 1

2. Two substance A and B are present [A] = 4 [B]. The half life of A is 5 minute and that of B is15 minute. If they start decaying at the same time following first order kinetics howmuch time later the concentration of both of them would be same(A) 15 minute (B) 10 minute(C) 5 minute (D) 12 minute

3. A solution of sodium sulphate in water is electrolysed using platinum electrodes. Theproducts at cathode and anode are respectively.(A) H2, O2 (B) O2, H2(C) O2, Na (D) O2, SO2

4.M(OH)xhas KSP4 1012and solubility 104M. Then the value of x is

(A) 1 (B) 2

(C) 3 (D) 4

5. A mixture of two immiscible liquids nitrobenzene & water boiling at 99 C has a partial vapourpressure of water 733 mm & that of nitrobenzene 27 mm. The ratio of the weights ofnitrobenzene to the water in the distillate is(A) 2:1 (B) 4:1(C) 3:1 (D) 1:4

6.Solubilites of carbonates decreases down the magnesium group due to decrease in(A) entropy of solution formation (B) lattice energies of solids(C) hydration energy of cations (D) inter-ionic attraction

7. Boric acid is prepared from borax by the action of

(A) 2 4H SO (B) NaOH(C)

2CO (D)

2 3Na CO

8. Which of the following ions can cause coagulation of proteins?(A) Ag+ (B) Fe3+(C) Cu+ (D) Ni2+

9. For the reaction,

C7H8(l) + 9O2(g) 7CO2(g) + 4H2O(l), the calculated heat of reaction is 232 kJ/moland observed heat of reaction is 50.4 kJ/mol, then the resonance energy is(A)182.2 kJ / mol (B) + 182.2 kJ / mol(C) 172 kJ/ mol (D) None

10. If 0.5 mole of2BaCl is mixed with 0.2 mol of 3 4Na PO , the maximum amount of 3 4 2Ba (PO ) that

can be formed is:(A) 0.7 mol (B) 0.5 mol(C) 0.2 mol (D) 0.1 mol


2/15

11.In a face centered cubic arrangement of X and Y atoms, whose Y atoms are at the corner ofthe unit cell and X-atoms at the face centers. One of the X-atoms is missing from

one of the faces in the unit cell. The simplest formula of the compound is(A) X5Y2

(B) X2Y5(C) XY3 (D) X3Y

12. A box of 1 litre capacity is divided into two equal compartments by a thin partition which arefilled with 6g H2 and 16g CH4 respectively. The pressure in each compartment isrecorded as P atm. The total pressure when partition is removed will be(A) P (B) 2P(C) P/2 (D) P/4

13. Aniline reacts with phosgene and KOH to form(A) OH

(B)

C

O

Cl

(C) NHCOCl

(D) NCO

14.Which of the following can not be oxidized by

2 2H O ?

(A) KI + HCl (B)3

O

(C) PbS (D)2 3

Na SO

15.Which of the following is present in maximum amount in acid rain?

(A)3

HNO (B)2 4

H SO

(C) HCl (D)2 3

H CO

16. In Nesslers reagent for the detection of NH3, the active species is

(A) Hg2Cl2 (B) HgI2

(C) Hg2I2 (D) HgI42

17. If pressure is applied to the following equilibrium, liquid vapours the boiling point ofliquid(A) will increase (B) will decrease(C) may increase or decrease (D) will not change

18. The types of bond present in ZnSO4.7H2O are only

(A) Electrovalent and covalent

(B) Electrovalent and co-ordinate

(C) Electrovalent, Covalent and co- ordinate

(D) None of these


3/15

19. End product of the reaction|| ||

3 2 2 2

O O

H C C CH CH CH COH 42

1.NaBH

2.H O, H is

(A)

O

CH3

O

(B)

O

O

CH3

(C) H3CHC

OH

CH2CH2CH2CH2OH

(D)

CH3C

O

CH2CH2CH2CH2OH20. The order of reactivities of the following alkyl halides for SN 2reaction is:

(A) RF > RCl > RBr > RI (B) RF > RBr > RCl > RI(C) RCl > RBr > RF > RI (D) RI > RBr > RCl > RF

21.

CH2Cl2Anhyd.

AlCl3

Z

Excess

Z is

(A)

CH2Cl

(B)

CHCl2

(C)

(D)

CH2

22.Which of the following will not give aldol condensation?(A) RCH2CHO (B) RCOCH2R(C) C6H5CHO (D) C6H5CH2CHO

23. A mixture of benzoic acid and phenol may be separate by treatment with

(A) NaHCO3 (B) NaOH

(C) NH3solution (D) KOH

24.

CH3 C CH2

CH3

O

182H O

H A, A is


4/15

(A)

CH3 C

CH3

OH

CH2

OH18

(B)

CH3 C

CH3

OH

CH2

OH18

(C) Both (D) none

25.2-acetoxy benzoic acid is called(A) antiseptic (B) aspirin(C) antibiotic (D) mordant dye

26.CH

3

CH CH CH2

CH3

HBr A (predominant). A is

(A) CH3 CH CH CH3

CH3 Br

(B) CH3 CH CH2 CH2Br

CH3 (C)

CH3 C CH2 CH3

CH3

Br

(D) None is correct

27.Consider the following reaction

CH3 CH CH CH3

D CH3

Br 'X' HBr

Identify the structure of the product X

(A) H3C CH CH CH2

D CH3

(B) H3C CH C CH3

D CH3 (C) H3C C CH CH3

D CH3

(D) H3C CH CH CH3

CH3


5/15

28. The IUPAC nameof

(C2H5)2NCH2CH COOH is

Cl (A) 2chloro4(Nethyl) pentanone acid(B) 2chloro3(N, Ndiethyl amino) propanoic acid

(C) 2chloro2oxo diethyl amine(D) 2chloro2carboxyNethyl ethane

29. In the commercial electrochemical process for aluminium extraction, the electrolyte used is(A)

3Al(OH) in NaOH solution

(B) An aqueous solution of2 4 3

Al (SO )

(C) A molten mixture of2 3 3 6Al O andNa AlF

(D) A molten mixture of2 3 3

Al O and Al(OH)

30. Which substance is not present in nucleic acids?(A) cytosine (B) adenine(C) thymine (D) guanidine

SOLUTION

1. Circumference of 3rdorbit = 2r3

According to Bohrs angular momentum of electron in 3rdorbit is

mvr3= h32

or 32 rhmv 3

By de-Broglie equation,

=h

mv

= 32 r

3

2r3= 3i.e. circumference of 3rdorbit is three times the wavelength of electron or number of

waves made by Bohr electron in one complete revolution in 3rdorbit is three.

(B)

2.Amount of A in n1halves =

1n

0

1

A2

Amount of B in n2halves =

2n

0

1B

2

If

1n

0

1A

2=

2n

0

1B

2When A decays to n1halves and B decays to n2halves

0A = 4 0B


6/15

4 = 1

1 2

2

nn n

1 2n

22 (n n ) 2

2

n2= (n1-2) (1)

Now t = n1t1/2(A) = n2t2(B)=

1

2

n 51

n 15

1

2

n 3n

(2)

by (1) & (2) n1= 3, n2=1 t=35 = 15 minute

(A)

3.Discharge potential of H+is less than Na+and OHis less than 24SO .

Hence, (A)is correct

4. M(OH)xwill ionize in the way

M(OH)x M+

x + xOH

104 x104

Ksp= [M+x] [OH]x (104) (x104)x= 4 1012

by inspection we get this relation will hold good whenx= 2

(B).

5.M A

P' P X

Where XAis mole fraction in gaseous phase.

2

1 2

W /12327 760 for nitrobenzene

W W

18 123

& 21 2

W /18733 760

W W

18 123

1

2

W4

W

(B)6. (C) Hydration energy decreases as size of cation increases.

7.A

8.C

9.(A) As we know that,

Resonance energy = H (observed)H (calculated)= (50.4232.6) kJ / mol

=182.2 kJ mol1

10. Let us first solve this problem by writing the complete balanced reaction.

2 3 4 3 4 23BaCl + 2 Na PO Ba (PO ) + 6NaCl

We can see that the moles of2BaCl used is

3

2times the moles of

3 4Na PO .


7/15

So, to react with 0.2 mol of3 4

Na PO , the moles of BaCl2 required would be3

0.22

=

0.3. Since2BaCl is 0.5mol, we can conclude that 3 4Na PO is the limiting reagent.

Therefore, moles of3 4 2

Ba (PO ) formed is1

0.22

= 0.1 mol.

11.A

12.AAs pressure in each compartment is P atm, after the partition is removed the total pressurewill be P atm.

13.

2 2PhNH COCl KOH Ph NCO

Hence (D) is correct.

14.B3

O is more powerful oxidizing agent than2 2H O . So 2 2H O reduces 3O to 2O .

3 2 2 2 2O H O H O 2O

15.B

16.D

17.ABoiling point of a liquid is the temperature at which vapour pressure became equal to

atm pressure. If the pressure is applied to the above equilibrium the reaction will go to thebackward direction, i.e. vapour pressure decrease hence the boiling point increase.

18.C

19 A NaBH4reduces ketonic group but not acidic groupCH3 CH

OH

CH2 CH2 CH2 COOH

is the intermediate which forms cyclic ester.

O

CH3

O

20.D

21.D22.C Aldol condensation is given by those carbonyl compounds, which possess at least

one - H.

(C) is not having hydrogen hence it will not give aldol condensation

23.A

24.A Stability of carbocation is 3> 2> 1


8/15

25.(B)

26.(C).

CH3 CH CH2

CH3

HCH3 CH CH

CH3

CH3

1, 2 H shiftCH3 C CH2

CH3

CH3Br

CH3 C CH2

CH3

CH3

Br

27.B more stable free radical will be formed as an intermediate

28.B

29.C

30.D Nitrogenous base in nucleic acids are Purine - Adenine and guanine Pyrimidine Cytosine and Thymine or uracil

CHEMISTRY PAPER 21.If the radius of 2ndBohr orbit of hydrogen atom is r2. The radius of third Bohr orbit will be

(A)2

4r

9 (B) 4r2

(C) 29

r4

(D) 9r2

2. The chemical reaction 203302proceeds as following:O3 O2+ O (fast)

O + O32O2(slow)The rate expression should be(A) r= KI[O3]

2 (B) r= KI(O3)2[O2]

-1(C) r = KI[O3] [O2] (D) unpredictable

3. A certain current liberated 0.504 g of hydrogen in 2 hours. How many grams of copper can beliberated by the same current flowing for the same time in CuSO4solution?(A) 12.7 g (B) 15.9 g(C)31.8 g (D) 63.5 g

4. The hydrolysis constant for ZnCl2will be

(A) Kh=Kw

Kb

(B)2

KwK =

h Kb

(C) Kh=2

Kw

2Kb

(D)K

bK =

h 2Kw


9/15

Where Kbis effective dissociation constant of base Zn++

5. Dry air was passed successively through a solution of 5 gm of a solute in 180 gm of waterand then through pure water. The loss in weight of solution was 2.50 gm and that ofpure solvent is 0.04 gm. The molecular weight of the solute is(A) 31.25 (B) 3.125(C) 312.5 (D) none of these

6. AlCl3forms dimmer in vapour phase but BCl3dose not because(A) In Al there are vacant d orbitals in which it accommodates lone pair from chlorine

atoms(B) In BCl3there is back bonding(C) There is hydrogen bonding in between two AlCl3molecules in vapour phase(D) None of the above

.7. The paramagnetic species is

(A)2KO (B) 2SiO

(C)2TiO (D) 2BaO

8. Which of the following is less than zero during adsorption?

(A) G (B) S

(C) H (D) All the above

9 The difference between heats of reaction at constant pressure and constant volume for the

reaction

6 6 2 2 22C H 15O g 12CO g 6H O at 25C in KJ mol1is

(A) 7.43 KJmol1 (B) 7.43 KJmol1

(C) 2.477 KJmol1 (D) 2.477 KJmol1

10.Equal volumes of 1 M each of 4 2 2 7KMnO and K Cr O are used to oxidise Fe(II) solution in acidic

medium. The amount of Fe oxidized will be(A) more with

4KMnO (B) equal with both oxidizing agents

(C) more with2 2 7

K Cr O (D) cannot be determined

11. A solid crystal is composed of X, Y and Z atoms. Y atoms are occupying 50% of octahedral

voids, where as X atoms are occupying the 100% tetrahedral void with Z atoms

in ccp array arrangement, then the rational formula of the compound in the given

crystal is

(A) X8Y2Z4 (B) X5Y10Z8

(C) X4YZ2 (D) X16Y4Z8


10/15

12. An LPG cylinder contains 15 kg of butane gas at 27C and 10 atmospheric pressure.It was leaking and its pressure fell down to 8 atmospheric pressure after one day.

The gas leaked is:(A)1kg (B) 2 kg(C)3 kg (D) 4 kg

13. Which of the following reactions will not give primary amine?

(A) 2Br /KOH3 2CH CONH (B)

4LiAlH3CH CN

(C) 4LiAlH3CH NC (D)4LiAlH

3 2CH CONH

14 When the same amount of zinc is treated separately with excess of sulphuric acid andexcess of sodium hydroxide, the ratio of volumes of hydrogen evolved is(A) 1 : 1 (B) 1 : 2(C) 2 : 1 (D) 9 : 4

15. Which of the following has greatest affinity for haemoglobin :(A) CO (B) NO

(C)2

O (D) 2CO

16. The basic character of the transition metal monoxides follows the order(A) CrO > VO > FeO > TiO (B) TiO > FeO > VO > CrO(C) TiO > VO > CrO > FeO (D) VO > CrO > TiO > FeO

17. The enthalpies of two reaction are H1 and H2 (both positive) with

H2H1. If the temperature of reacting system is increased from T1to T2, predictwhich of the following alternatives is correct?

(A)

1 2

1 2

K K=

K K

(B)

1 2

1 2

K K>

K K

(C)

1 2

1 2

K K

chemistry jee main

Documents