Target Eng-2019 JEE MAIN OFFICIAL ONLINE EXAM / 9 January 19 Slot I / Solutions ANSWERKEY Date: 09 Jan 2019 1
1. Heat and thermodynamics, Equivalent thermal resistance 2. Heat and thermodynamics, Required ratio 3. Rotational Motion, Torque balance about A 2
4. Current electricity, 5. B Heat and thermodynamics, 6. Wave Motion, 3
7. Electrostatics, On the axis of a ring When E is maximum, 8. Electrostatics, 9. Ray Optics, Taking the angle of incidence 4
10. Kinematics, 11. Newton's Laws of motion, 12. Di iculty : Di icult Capacitors, Taking an element of thickness dx at a distance of x from the le 5
13. Ray Optics, Shi due to sleb 14. Modern Physics, 15. ELECTROMAGNETISM, Coercivity 16. Current electricity, 6
17. Di iculty : Di icult ELECTROMAGNETISM, 18. Modern Physics, Solving 19. Semiconductors, Resistivity 20. System of particles, 7
21. MAGNETISM, 22. Rotational Motion, 23. Heat and thermodynamics, 24. Work,Energy and power, Momentum speed is in equilibrium 8
25. Current electricity, Red = 2 Violet = 7 Orange = 3 Silver = 10% 26. ELECTROMAGNETISM, 27. Current electricity, 28. Rotational Motion, Distance of centre of mass from 9
29. ELECTROMAGNETISM, 30. Wave optics, - CHEMISTRY 1. Chemical Bonding, has total of 5 electron Molecular orbital configuration of is Bond order has 7 electron M.O.T configuration of is Bond order & have same bond order but has no electron in antibonding orbitals, while has one electron in antibonding orbital. Hence, is more stable than 10
2. CARBOXYLIC ACIDS AND ITS DERIVATIVES, 3. Aromatic compounds, 4. Thermodynamics, Plot between W and ln V having negative intercept. 11
5. Surface Chemistry, According to Freundlich adsorption isotherm 6. Chemical Kinetics,... (1)... (2)... (3) using using Rate equation 12
7. Ionic equilibrium, Taken millimoles 2 6 reacted 2 4 2 le 0 2 2 Resultant is a bu er of weak base and it salt with strong acid. 8. Atomic Structure, 13
9. Metallurgy, azurite dolomite copper pyrites malachite 10. Chemistry, Henry's law 11. Alkenes, 12. P-block-II, Inert pair e ect for heavier elements, stabilities of lower oxidation state increases due to inert behavior of electrons. 14
13. GOC, A strong acid has a weak conjugate base. being a withdrawing group makes the pair of electrons on carbon more delocalized in the conjugate base Order of e ect is 14. PERIODIC PROPERTIES, for 1 mole of charge is required. for 15. Chemistry, For Mn allowable level is 0.05 PPM. 16. BIOMOLECULES, Down the group electronegativity decreases (due to increase in atomic radius ) Atomic radius Increases (due to addition of extra shell ) 15
17. Chemistry, 18. Alkenes, Alcohols, 19. Acids, Polymers, 16
20. Chemistry, Greater the -I e ect, greater is the acidity. Order of e ect is 21. Environmental Chemistry, Properties of silicones. 22. Liquid Solutions, 23. P-block-II, Energies are calculated for on the basis of absorbed light, not by the emitted light. 24. Atomic Structure, Maximum number of unpaired electrons in any transition metal complex are 5. Spin only magnetic moment 17
25. Chemistry, Piezeo electric susbstance produce dipole by applying pressure. 26. Di iculty : Di icult Polymers, Due to very low polazising power of ions. 27. Phenols, 18
28. Di iculty : Di icult Thermodynamics, 29. BIOMOLECULES, Arginine PI = 10.8 Lysine PI = 9.8 Glycine PI = 6.0 Aspartate PI = 3.0 Asp < Gly < Lys < Arg 19
30. Solutions, The lone pair is localised in hybrid orbital in In the lone pair is localised in hybrid orbital (not involved in resonance) 1. In the lone pair is involved in delocalisation in aromaticity. MATHEMATICS Complex Numbers, is purely imaginary i.e. real part Sum: 20
2. Three Dimensional Geometry,...(1) to...(2) (1) intersects...(3)...(2) is: 3. Parabola, Parabola : does not lie on it. 21
4. STATISTICS,...(1) New variance : 5. Sequence & Series,...(1) Common di erence...(2)...(3) Now 22
6. Permutations & Combinations, 5 girls, 7 boys and 5 others We need to make team of 3 boys and 2 girls. Such that and cannot come together. Nither of either or 7. Probability, 8. Application of derivatives, Points of intersection of and are 23
9. Determinants & Matrices, put 10. Mathematics, Logic, 24
11. Complex Numbers, 25
12. Parabola, Circle : Centre : radius : 3 Parabola : tangent to parabola :...(1) If it is tangent of circle, then perpendicular from on (1) = radius in (1) Now take 26
13. TRIGONOMETRY, Expression : 14. Circles, 27
15. Determinants & Matrices,...(1)...(2)...(3) If if at least one of system is inconsistent. 28
16. Di erential Equations, linear di erential equation I.F. Solutions : 17. Three Dimensional Geometry, Plane through intersection of and is is to y-axis point satisfies above plane. 29
18. Straight lines,...(1) putting in (1) lines are concurrent at 19. Vectors, let...(1) 30
20. Area under curve, tangent: Area required : 21. Binomial Theorem, i.e., we need remainder when is divided by 31
22. Definite integration, 32
23. Indefinite integration, 33
24. Sequence & Series, distinct no. in G.P. is common ratio When as i.e. 25. Limits, rationalising : again rationalizing : 34
26. Inverse Trigonometric Functions, 27. ContinuityDi erentiability & Derivatives, Continuous at...(1) Continuous at...(2) (1) and (2) Continuous at...(3) (1), (2), (3) are not justified simultaneously. 35
28. Hyperbola, length of latus rectum : Latus rectum 29. Application of derivatives, 36
30. Functions, Given 37