JEE MAIN EXAM 2017 Solutions / CODE A

Transcription

1 / JEE - MAIN EXAM / Solutions / CODE - A JEE MAIN EXAM 2017 Solutions / CODE A Date: 02 Apr

2 1. Elasticity, 2. Kinematics, Velocity becomes negative a er same time and the negative slope is constant. 3. Work,Energy and power, 2

3 4. Work,Energy and power, or or or or At 5. Rotational Mechanics, 3

4 6. Rotational Mechanics, Torque of gravity about or 7. Gravitation, The desired graph is 4

5 8. Caloriemetry, Heat lost by ball = Heat gain by calmimetre and water 9. Elasticity, and or 10. Physics, Heat and thermodynamics, for hydrogen for nitrogen 5

6 11. Physics, Heat and thermodynamics, 12. Simple harmonic motion, The period of K.E graph is half of the period of displacement graph. Comment :- The points on the graph on -axis should be di erentiable. In all option mentioned, the graph has cusps at the points on -axis. 13. Wave optics, 6

7 14. Electrostatics, Since plane Consider dipole moment is in According to the problem 15. Capacitors, 8 rows, then Get So minimum of capacitors are 7

8 16. Current electricity, By KVL : - So charge on capacitor is 17. Current electricity, P.d across each resistor is zero. Hence correct is zero in each resistor. 18. Physics, Topic : Classical Magnetism Time period 8

9 19. Current electricity, or or or or 20. Electromagnetic Induction( EMI ), or or or or or 9

10 21. Modern Physics, or The graph of Vs is as follows 22. Ray Optics, Diverging lens forms the image at its focus. The image formed by diverging lens in the object to converging lens. Distance of the object from converging lens is i.e., object is at double focal point. Image forms at double focal point on the other side of the lens. 10

11 23. Wave optics, 4 th Bright of will coincide with 5 th bright of 24. Modern Physics, 11

12 25. Modern Physics, 26. Modern Physics, no. of undecayed nucleus no. of decyaed nucleus is 27. Physics, Topic - Semiconductor Voltage gain of the amplifier is -Ve sign indicates phase di erence is 12

13 28. Physics, Topic - Communication System will not be there in the frequencies. 29. Current electricity, Null point does not change 30. Surface tension, 13

14 31. Topic : Thermochemistry...(1)...(2) (1)+2 (2) and +(3)...(3) 32. Mole concept, 33. Thermodynamics, From First law of Thermodynamics for an Adiabatic process 34. Surface Tyndall e ect is observed when (1) The diameter fo the dispersed particle is not much smaller than the wavelength of the light used. (2) The refractive indices of the dispersed phase and dispersion medium di er greatly in magnitude. 14

15 35. Solid State, Distance of closest approach 36. Electrochemistry,, Strongest reducing agent is the atom/ ion which is easily oxidised i.e. having the largest value of standard oxidation potential (SOP) is the maximum value. 37. Solutions, Since, or 15

16 38. Atomic Structure, ; n = orbit number, 39. Chemical Kinetics, (At 300K) 40. Ionic equilibrium, For the hydrolysis of a salt of weak acid and weak base 41. Di iculty : Di icult S-block, form basic carbonate while lithium from normal carbonate. 16

17 42. Chemical Bonding, is diamagnetic only and has bond order 3.0. Rest all are paramagnetic 43. P-block, 44. Topic : Environmental science ppm causes brown mottling of teeth ppm causes laxative ppm causes blue baby syndrome. 45. Topic : Periodic properties in each species (all are isoelectronic). 17

18 46. S-block, cold - dil 47. d-block, 48. Di iculty : Di icult Topic : Qualitative analysis is responsible for decolourisation of acidic solution of. 49. Mole concept, is by mass is kgs It replaced by weight is doubled i.e., kg kg increase 18

19 50. Di iculty : Di icult Topic : coordination No of moles of ions moles. moles of gives moles of ions No. of outside the co - ordination sphere should be Topic - Nitrogen containing compounds Aniline undergoes protination in con, so it undergoes metanitration 52. Topic - Alkylhalides To shown decolourisation compound must be unsaturated 19

20 53. Polymers, Nylon - 6 is prepared from caprolactum,caprolactum on hydrolysis it gives aminocarboxylicacid it undergoes polymerisation to form Nylon GOC, Non aromatic compunds are less stable than aromatic 20

21 55. Topic - Alkylhalides Rate of stabiling 56. Topic - Hydrocarbons 21

22 57. Di iculty : Di icult Topic - Carbohydrates Sugar with hemiacetal are reducing sugar. 58. Topic - Hydrocarbons Product contains two chiral carbons so, 4 S.I 22

23 59. Di iculty : Di icult CARBONYLS, 60. Di iculty : Di icult CARBONYLS, DIBAL-H can reduce esters only, not carboxylicacids 23

24 61. Functions, One-One Function (Injection), Onto Function (Surjection), is many one Range = Co-domain 62. Quadratic Equations, as 24

25 63. Complex Numbers, Cube roots of unity, i.e. is non-real cube root of unity and 64. Determinants & Matrices, Adjoint of square Matrix, 65. Determinants & Matrices, Cramer's Rule, As system no solution then when then both equation and obeserv that if then no solutions if then infinite solutions 25

26 66. Permutations & Combinations, 67. Binomial Theorem, 68. Sequence & Series, are in AP 26

27 69. Sequence & Series, Functions, 70. Limits, 27

28 71. Math, Di erentiation of one function with respect to another function, Put and as 72. Application of derivatives, Equation of normal at will be which is satisfied by only in the given options. 28

29 73. Application of derivatives, 74. Math, Indefinite integration, (Put n = 4) 29

30 75. Math, Definite integration, 76. Di iculty : Di icult Math, Area under curve, Required area 30

31 77. Di erential Equations,...(I) I.F. of equation (I) is Hence answer is As So Now 78. Straight lines, or as Triangle has co-ordinates As one side is horizontal one altitude will be vertical arthocentre 31

32 79. Circles, Conic Sections, If the radius of circle is r, then its centre will be In an isoscales right angled 80. above, Remark : Observe that the required circle does not have to touch both the rays hence the radius of such circle can be as small as one wishes. Hence minimum radius does not exist. (However infimum radius is zero.) Conic Sections, Again and Hence equation of ellipse is and equation of normal at point is: Equation of normal at point is 32

33 81. Math, Conic Sections, Which is satisfied by 82. Math, Three Dimensional Geometry, Normal perpendicular to both the lines Normal vector parallel to perpendicular where Hence equation of plane is Now distance from point (1, 3, -7) to the plane is 33

34 83. Math, Three Dimensional Geometry, Line PQ parallel to As point R lies on plane then Hence point R is (2, 2, 8) 84. Math, Vectors, Using (2) in (1) we have 34

35 85. Math, Probability, n = number of trials = 10 p = probability of drawing green ball = probability of success q = probability of failure As the trials are Bernoulli trials, variance = npq 86. Math, Probability, P(Exactly one of A or B occurs) Adding all three P (Atleast one event occurs) = 35

36 87. Math, Probability, Two di erent numbers are taken from the set Let x + y = 4m...(II) x - y = 4n... (III), x > y Now x = 2(m+n) y = 2(m-n) Hence both x and y are even numbers Then x and y are both in form of 4k or 4k + 2 So order pair of (x, y) are So Probability 88. Math, Trigonometric Ratios & Identities, 36

37 89. Math, Topic : Height & Distance 90. Math, Topic : Mathematical Reasoning T T T F T T T T F F F T F T F T T T T T T F F T T F T T Hence it is a Tautology Alternate : 37