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Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions Target Eng-2018 Rao IIT Academy JEE ADVANCED EXAM 2018 / PAPER - 2 Solutions Date: 20 May 2018 1. Diiculty : Medium Topics : Work ,Energy and power, Speed is proportional to time hence force is constant Force is constant, hence conservative Correct options are (ABD) Rao IIT Academy Website : www.raoiit.com 1 PHYSICS

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Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

Target Eng-2018 Rao IIT Academy JEE ­ ADVANCED

EXAM ­ 2018 / PAPER - 2 Solutions

Date: 20 May 2018

1. Di�iculty : Medium

Topics :

Work ,Energy and power,

Speed is proportional to time

hence force is constant

Force is constant, hence conservative

 Correct options are (ABD)

Rao IIT Academy Website : www.raoiit.com1

PHYSICS

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

2.Di�iculty : Easy

Topics :

Viscosity newton's law of viscosity,

hence correct options (ACD)

3. Di�iculty : Medium

Topics :

Electrostatics,

and its component along  -axis will be zero

hence correct options (AB).

Rao IIT Academy Website : www.raoiit.com2

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

4. Di�iculty : Di�icult

Topics :

Ray Optics,

 

       

So option (D) is correct.

5. Di�iculty : Easy

Topics :

Modern Physics,

Hence correct options (A) and (C)

Rao IIT Academy Website : www.raoiit.com3

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

6.Di�iculty : Di�icult

Topics :

Sound wave,

subtracting two equations

 Correct option (A) and (C)

7. Di�iculty : Medium

Topics :

System of particles,

            

Rao IIT Academy Website : www.raoiit.com4

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

8.Di�iculty : Medium

Topics :

Kinematics,

                 

                                   

                                                         

9.Di�iculty : Di�icult

Topics :

Kinematics,

Rao IIT Academy Website : www.raoiit.com5

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

10. Di�iculty : Medium

Topics :

Current electricity,

round o� two decimal

11. Di�iculty : Medium

Topics :

Experiments based on using verniercalipers and screw gauge ( micrometer ),

     

     

                  

             

Rao IIT Academy Website : www.raoiit.com6

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

12. Di�iculty : Easy

Topics :

Thermodynamics,

13.Di�iculty : Medium

Topics :

Modern Physics,Photoelectric e�ect,

      

      

Rao IIT Academy Website : www.raoiit.com7

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

14. Di�iculty : Easy

Topics :

Bohr’s model of an atom,

15. Di�iculty : Easy

Topics :

Electrostatics,

(1)  Point charge at origin 

(2)  

(3)  Uniform line charge 

(4)  

       

(5)  Infinite plane charge   constant

Rao IIT Academy Website : www.raoiit.com8

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

16. Di�iculty : Medium

Topics :

Gravitation,

                                           

                     

                 

                

                         

17. Di�iculty : Medium

Topics :

Thermodynamics,

Process (1) is adiabatic

Process (2) is isobaric

Process (3) is isochoric 

Process (4) is isothermal

Rao IIT Academy Website : www.raoiit.com9

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

18.Di�iculty : Di�icult

Topics :

Rotational Mechanics,

(P)  

     

     

      hence all conserved

      

(S)  

       

       

         not conserved

         is only conserved

       

(R)  

       

       

       

         conserved

       

(Q)  

       

       

       

       

         conserved

       

hnce option (A)

Rao IIT Academy Website : www.raoiit.com10

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

1.Di�iculty : Medium

Topics :

Coordination Compounds,

(A)    has two geometrical isomers.

       

(B)  If bidentate  is replaced by two cyanide ligands.

       

(C)  

       In presence of 

       

       Therefore it is diamagnetic in nature.

(D)    is weaker ligand than  , so   absorbs light at longer wavelength as compared

to  .

2.Di�iculty : Di�icult

Topics :

Qualitative analysis,

(A)    and   both show characteristic green colour in the flame test, so can't be distinguished.

(B)  Only  can give precipitate of   when passing   in acidic medium.

(C)    and   both show precipitate by passing   in faintly basic medium.

(D)  From electrochemical series 

                                                

Rao IIT Academy Website : www.raoiit.com11

CHEMISTRY

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

3. Di�iculty : Medium

Topics :

Aromatic compounds,

Rao IIT Academy Website : www.raoiit.com12

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

4. Di�iculty : Easy

Topics :

Polymers,BIOMOLECULES ,

 glucopyranose

5.Di�iculty : Medium

Topics :

Chemical Kinetics,

                  

                                        

                                      

     

or

Comparing with  So it is a straight line with negative slope.

For   _______

 constant

rate constant   does not depend on concentration

Rao IIT Academy Website : www.raoiit.com13

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

6. Di�iculty : Di�icult

Topics :

Chemical equilibrium,

 

That measn on increasing temperature reaction is shi�ing in backward direction, so it is exothermic reaction i.e., 

It is possible when   because   (given)

   at equilibrium

Rao IIT Academy Website : www.raoiit.com14

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

7. Di�iculty : Medium

Topics :

P-block,

Therefore   and   have at least one bridging oxo group.Rao IIT Academy Website : www.raoiit.com15

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

8. Di�iculty : Di�icult

Topics :

Mole concept,Metallurgy,

Noumber of equivalents of 

                           

                           

9. Di�iculty : Easy

Topics :

Volumetric analysis,

m.eq of

       ......... (1)

From given equation __________

            .......... (2)

Because   of   is   in both equations, so

10. Di�iculty : Di�icult

Topics :

Stereochemistry,

 One meso compound and 7 optically active isomers formed.

Rao IIT Academy Website : www.raoiit.com16

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

11.Di�iculty : Medium

Topics :

Aromatic compounds,

12. Di�iculty : Medium

Topics :

Thermodynamics,

______________________________________________________________________________

 

To prevent this reaction, 

 ......... ( considering equality for minimum  )

Minimum 

Rao IIT Academy Website : www.raoiit.com17

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

13. Di�iculty : Medium

Topics :

Chemical Kinetics,

          ......... (i)

            ......... (ii)

equation (i) - (ii) 

                

            

            

absolute value is 

Rao IIT Academy Website : www.raoiit.com18

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

14.Di�iculty : Medium

Topics :

Electrochemistry,

________________________________________

             

         

                                   

                                     

Rao IIT Academy Website : www.raoiit.com19

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

15. Di�iculty : Medium

Topics :

Coordination Compounds,

(1) 

   

(2)             

(3)            

(4)  

       

(5)  

      

      due to   back pairing of   takes place

      

(6)  

      

      Due to   electron pairing takes place

      

Rao IIT Academy Website : www.raoiit.com20

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

16. Di�iculty : Medium

Topics :

Alcohols,Ethers,

Rao IIT Academy Website : www.raoiit.com21

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

17.Di�iculty : Medium

Topics :

Alkyl halides,

Rao IIT Academy Website : www.raoiit.com22

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

18. Di�iculty : Medium

Topics :

Ionic equilibrium,

P. 

      m. moles   m. moles   so a�er reaction,   will existas an acidic bu�er and its   or   is independent of dilution.

 

Q.   m. moles   m. moles  only   (salt)  exists in solution. From salthydrolysis concept ________

      ........ (for salt of weak acid and strong base)

 changes to   times

R. m. moles   m. moles  only   (salt of w. base and st. acid) will exist in solution

     ......... (from salf hydrolysis)

    

     

                 ......... (  

S.   Because   remains constant, so solubility of salt will not be changed, hence   or   will not be changeda�er dilution.

Rao IIT Academy Website : www.raoiit.com23

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

MATHEMATICS

. .1.

Di�iculty : Easy

Topics :

Inverse Trigonometric Functions,Limits,

(A) Zero is not in domain

(B) Zero is not in domain

(C) 

       (C is incorrect)

(D) 

                                                           (D is correct)

Rao IIT Academy Website : www.raoiit.com24

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

2.Di�iculty : Medium

Topics :

Circles,

Let  

and

       

and  

Also  

Thus   lies on circle with points   and   as diameter.

 Locus of   is 

 does not lie on    (D is correct)

Let midpoint of chord of   be

 is 

Equation of chord is 

Locus of midpoint of such chords passing through   is

 lies on     B is incorrect

 does not lie on    C is incorrect

 does not lie on     D is correct

Also      A is incorrect

Rao IIT Academy Website : www.raoiit.com25

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

3.Di�iculty : Di�icult

Topics :

Determinants & Matrices,

              ...(i)                        ...(ii)

                  ...(iii)      

Eq. (ii) + 2 eq (i) gives          

Eq (ii) - 2eq (iii) gives             

                             

                                     original condition

(A)      unique solution

(B)             ...(i)                                         ...(ii)

          ...(iii)  

   

        we get

                                      

 for infinite solutions 

                                    

 which is not the original condition.

 It does not have a solution.

(C)           ...(i)                            ...(ii) 

                  ...(iii)

Clearly planes are parallel   for infinite solution which can be true considering original condition.

(D)                             

     

    It has a solution.

Rao IIT Academy Website : www.raoiit.com26

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

4.Di�iculty : Easy

Topics :

Circles,Ellipse,Conics,Area under curve,

                                            

Let equation of common tangent be 

                            

                                        

                           

One of the lines is                           

For ellipse 

 Equation of ellipse is                        

  also    (A is correct)       For    Area bounded by   and   is    

Area              

                                     

          

           C is correct.

Rao IIT Academy Website : www.raoiit.com27

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

5.Di�iculty : Di�icult

Topics :

Complex Numbers,

               ...eq (i)

               ...eq (ii)

 (eq i)   (eq ii) we get

(A) If   i.e.  It has unique solution   A is correct

(B)   may have infinite or no solution

(D) If   has more than one solution then no solution and unique solutions are ruled out.   It has infinite solution.

(C)   is a circle.

     If   has infinite solution then it lies on the line   line and circle may have atmost two solutions.

Rao IIT Academy Website : www.raoiit.com28

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

6.Di�iculty : Medium

Topics :

Limits,Application of derivatives,

     

Apply L'Hospital    

                

                                      

                    

  A is incorrect.

(B) Cosider 

    

   

      

                      

                      

       

       is decreasing                       

                                       

                                            is decreasing

                                       

                B is correct

(C) Apply Rolle's theorem in 

     

  for some    C is correct

(D) 

         D is correct

Rao IIT Academy Website : www.raoiit.com29

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

7 Di�iculty : Easy

Topics :

Definite integration,

Put 

Rao IIT Academy Website : www.raoiit.com30

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

8.Di�iculty : Di�icult

Topics :

Definite integration,

where   etc.

         

for max          

i.e.   but  and   are dependent there is no such combination of   s.t. each 

  and each 

Keeping symetrically,   anwser is not possible

let us see whether   is possible i.e.

 or   or 

Rao IIT Academy Website : www.raoiit.com31

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

9. Di�iculty : Easy

Topics :

Permutations & Combinations,

  number of one-one functions from X to Y

 number of onto functions from Y to X.

We have to distribute 7 items to 5 children such that each gets atleast one item.

Possible cases are

Rao IIT Academy Website : www.raoiit.com32

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

10. Di�iculty : Easy

Topics :

Di�erential Equations,

Rao IIT Academy Website : www.raoiit.com33

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

11.Di�iculty : Easy

Topics :

Functions,Di�erential Equations,

Put  

Put 

Rao IIT Academy Website : www.raoiit.com34

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

12.Di�iculty : Easy

Topics :

Three Dimensional Geometry,

Let the image of P ie Q be 

Image of Q about    is P

distance of P from x axis 

  is in first octant    

R is image of P about x - y plane.

Rao IIT Academy Website : www.raoiit.com35

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

13.Di�iculty : Easy

Topics :

Vectors,

Now 

     

required value 

Rao IIT Academy Website : www.raoiit.com36

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

14.Di�iculty : Easy

Topics :

Binomial Theorem,

Consider

    eq (i)

                            eq (ii)

Di�erentiate equation (i) we get

  eq (iii)

Required series is coe�icient of    in the product of eq (ii) and eq (iii)

coe�icient of   in 

Rao IIT Academy Website : www.raoiit.com37

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

15. Di�iculty : Easy

Topics :

Functions,

As    is negative

Also 

Range of

Its range contains (0,1) as well as

Also domain of f contains 

domain of g is 

Rao IIT Academy Website : www.raoiit.com38

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

16.Di�iculty : Easy

Topics :

Permutations & Combinations,

6 Boys: 

5 Girls :

(i) Committee of 5 has 3 boys and 2 girls 

                      

(ii) Atleast 2 members and equal boys and girls 

(iii)

(iv) Total ways of forming comitte of 4 with atleast 2 girls

Total ways of forming comittee of 4 with atleast 2 girls with  both included

 

      

Rao IIT Academy Website : www.raoiit.com39

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

17.Di�iculty : Easy

Topics :

Hyperbola,Conics,

     

                                                 

                                          

distance between foci is 

           

Rao IIT Academy Website : www.raoiit.com40

Rao IIT Academy / JEE - ADVANCED EXAM - 2018 / PAPER - 2 / Solutions

18 Di�iculty : Medium

Topics :

ContinuityDi�erentiability & Derivatives,

(i)                               

                                                          

           (both finite)                                         continuous but non di�erentiable

        at                                              

(ii)                                    

       Limit does not exist as                                discontinuous at 

       

(iii)                                         

                                                            

                                                    

       Hence it is di�erentiable and its derivatives is continuous at 

       

(iv)  

                                                    

       

       

         di�erentiable

      Now 

      

      Clearly discontinuous at                             is oscillatory          

Rao IIT Academy Website : www.raoiit.com41