Solved papers for JEE Main & Advanced JEE Main Paper (Held On 10-Jan-2019 Evening)

done JEE Main Paper (Held On 10-Jan-2019 Evening) Total Questions - 90

• question_answer1) Four equal point charges Q each are placed in the xy plane at\[\left( 0,\text{ }2 \right),\text{ }\left( 4,\text{ }2 \right),\text{ }\left( 4,\,-2 \right)\text{ }and\text{ }\left( 0,-\,2 \right)\]. The work required to put a fifth charge Q at the origin of the coordinate system will be- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]          
  A)
  \[\frac{{{Q}^{2}}}{4\pi {{\varepsilon }_{0}}}\]                        
  done clear
  B)
  \[\frac{{{Q}^{2}}}{2\sqrt{2}\pi {{\varepsilon }_{0}}}\]
  done clear
  C)
  \[\frac{{{Q}^{2}}}{4\pi {{\varepsilon }_{0}}}\left( 1+\frac{1}{\sqrt{3}} \right)\]
  done clear
  D)
                   \[\frac{{{Q}^{2}}}{4\pi {{\varepsilon }_{0}}}\left( 1+\frac{1}{\sqrt{5}} \right)\]
  done clear
  View Answer play_arrow

• question_answer2)             A rigid massless rod of length 3l has two masses attached at each end as shown in the figure. The rod is pivoted at point P on the horizontal axis (see figure).  When released  from initial horizontal position, its instantaneous angular acceleration will be- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{g}{13l}\]            
  done clear
  B)
  \[\frac{g}{2l}\]
  done clear
  C)
  \[\frac{g}{3l}\]              
  done clear
  D)
                   \[\frac{7g}{3l}\]
  done clear
  View Answer play_arrow

• question_answer3) A closed organ pipe has a fundamental frequency of 1.5 kHz. The number of overtones that can be distinctly heard by a person with this organ pipe will be (Assume that the highest frequency a person can hear is 20,000 Hz) [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  4                                             
  done clear
  B)
  7     
  done clear
  C)
  6   
  done clear
  D)
                   5
  done clear
  View Answer play_arrow

• question_answer4) Consider the nuclear fission \[N{{e}^{20}}\to 2H{{e}^{4}}+{{C}^{\text{12}}}\] Given that the binding energy/nucleon of\[N{{e}^{20}}\], \[H{{e}^{4}}\] and \[{{C}^{12}}\] are respectively, 8.03 MeV, 7.07 MeV and 7.86 MeV, identify the correct statement- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  8.3 MeV energy will be released
  done clear
  B)
  energy of 11.9 MeV has to be supplied
  done clear
  C)
  energy of 12.4 MeV will be supplied
  done clear
  D)
  energy of 3.6 MeV will be released
  done clear
  View Answer play_arrow

• question_answer5) A metal plate of area \[1\times {{10}^{-}}^{4}\,{{m}^{2}}\] is illuminated by a radiation of intensity\[16\text{ }mW/{{m}^{2}}\]. The work function of the metal is 5 eV. The energy of the incident photons is 10 eV and only \[10%\] of it produces photo electrons. The number of  emitted photoelectrons per second and their maximum energy, respectively, will be- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[{{10}^{14}}\] and 10 eV                   
  done clear
  B)
  \[{{10}^{12}}\] and 5 Ev
  done clear
  C)
  \[{{10}^{11}}\] and 5 eV
  done clear
  D)
                   \[{{10}^{10}}\]and 5 eV
  done clear
  View Answer play_arrow

• question_answer6) For the circuit shown below, the current through the Zener diode is-   [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  5 mA                           
  done clear
  B)
  zero
  done clear
  C)
  14 mA  
  done clear
  D)
                   9 mA
  done clear
  View Answer play_arrow

• question_answer7) Two vectors  \[\overrightarrow{A}\text{ }and\text{ }\overrightarrow{B}\] have equal magnitudes. The magnitude of \[\left( \overrightarrow{A}+\text{ }\overrightarrow{B} \right)\] is 'n' times the magnitude of\[\left( \overrightarrow{A}-\overrightarrow{B} \right)\]. The angle between \[\overrightarrow{A}\] and \[\overrightarrow{B}\] is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[{{\sin }^{-1}}\,\left[ \frac{n-1}{n+1} \right]\]               
  done clear
  B)
  \[{{\sin }^{-1}}\,\left[ \frac{{{n}^{2}}-1}{{{n}^{2}}+1} \right]\]
  done clear
  C)
  \[{{\cos }^{-1}}\,\left[ \frac{{{n}^{2}}-1}{{{n}^{2}}+1} \right]\]
  done clear
  D)
  \[{{\cos }^{-1}}\,\left[ \frac{n-1}{n+1} \right]\]
  done clear
  View Answer play_arrow

• question_answer8) The diameter and height of a cylinder are measured by a meter scale to be \[12.6\,\,\pm \,\,0.1\] cm and \[34.2\,\,\pm \,0.1\] cm, respectively. What will be the value of its volume in appropriate significant figures? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[4264.4\,\,\pm \,\,81.0\text{ }c{{m}^{3}}\]                  
  done clear
  B)
  \[4264\,\,\pm \,\,81c{{m}^{3}}\]
  done clear
  C)
  \[4300\,\,\pm \,\,80\text{ }c{{m}^{3}}\]
  done clear
  D)
                   \[4260\,\,\pm \,\,80\text{ }c{{m}^{3}}\]
  done clear
  View Answer play_arrow

• question_answer9) A current of 2 mA was passed through an unknown resistor which dissipated a power of 4.4 W. Dissipated power when an ideal power supply of 11 V is connected across it is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[11\times {{10}^{-5}}\text{ }W\]                     
  done clear
  B)
  \[11\times {{10}^{-3}}\text{ }W\]
  done clear
  C)
  \[11\times {{10}^{5}}\text{ }W\]          
  done clear
  D)
                   \[11\times {{10}^{-}}^{4}W\]
  done clear
  View Answer play_arrow

• question_answer10) Two stars of masses \[3\times {{10}^{31}}\] kg each, and at distance \[2\times {{10}^{11}}\] m rotate in a plane about their common centre of mass 0. A meteorite passes through 0 moving perpendicular to the star/s rotation plane. In order to escape from the gravitational field of this double star, the minimum speed that meteorite should have at 0 is-  (Take       Gravitational      constant;             \[G=6.67\times {{10}^{-11}}\,N{{m}^{2}}k{{g}^{-}}^{2})\] [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[2.4\times {{10}^{4}}m/s\]     
  done clear
  B)
  \[1.4\times {{10}^{5}}m/s\]
  done clear
  C)
  \[3.8\times {{10}^{4}}m/s\]
  done clear
  D)
  \[2.8\times {{10}^{5}}m/s\]
  done clear
  View Answer play_arrow

• question_answer11) Consider a Young's double slit experiment as shown in figure. What should be the slit separation d in terms of wavelength \[\lambda \] such that the first minima occurs directly in front of the slit\[\left( {{S}_{1}} \right)\]? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{\lambda }{2(5-\sqrt{2})}\]            
  done clear
  B)
  \[\frac{\lambda }{2(\sqrt{5}-2)}\]
  done clear
  C)
  \[\frac{\lambda }{(5-\sqrt{2})}\] 
  done clear
  D)
  \[\frac{\lambda }{(\sqrt{5}-2)}\]
  done clear
  View Answer play_arrow

• question_answer12) At some location on earth the horizontal component of earth's magnetic field\[18\times {{10}^{-}}^{6}T\]. At this location, magnetic needle of length 0.12 m and pole strength 1.8 Am is suspended from its mid-point using a thread, it makes \[45{}^\circ \] angle with horizontal in equilibrium. To keep this needle horizontal, the vertical force that should be applied at one of its ends is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[3.6\times {{10}^{-5}}\,N\]                             
  done clear
  B)
  \[1.8\times {{10}^{-5}}\text{ }N\]
  done clear
  C)
  \[1.3\times {{10}^{-5}}\,N\]     
  done clear
  D)
  \[6.5\times {{10}^{-5}}\,N\]
  done clear
  View Answer play_arrow

• question_answer13) Charges -q and +q located at A and B. respectively, constitute an electric dipole. Distance \[AB=2a\], 0 is the mid-point of the dipole and OP is perpendicular to AB. A charge Q is placed at P where \[OP=y\] and \[y\,\,>\,\,>\,\,2a\]. The charge Q experiences an electrostatic force F. If Q is now moved along the equatorial line to P? such that \[OP'=\left( \frac{y}{3} \right)\],  the force on Q will be close to- \[\left( \frac{y}{3}>>2a \right)\] [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  9F   
  done clear
  B)
  3F   
  done clear
  C)
  F/3                   
  done clear
  D)
                   27F
  done clear
  View Answer play_arrow

• question_answer14) The self-induced emf of a coil is 25 volts. When the current in it is changed at uniform rate from 10 A to 25 A in 1s, the change in the energy of the inductance is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  740 J                           
  done clear
  B)
  637.5 J
  done clear
  C)
  540 J   
  done clear
  D)
                   437.5 J
  done clear
  View Answer play_arrow

• question_answer15) Half mole of an ideal monoatomic gas is heated at constant pressure of 1 atm from\[20{}^\circ C\text{ }to\text{ }90{}^\circ C\]. Work done by gas is close to -(Gas constant \[R=8.31\text{ }J\] /mol. K) [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  581 J                           
  done clear
  B)
  73 J  
  done clear
  C)
  146 J   
  done clear
  D)
                   291 J
  done clear
  View Answer play_arrow

• question_answer16) Two kg of a monoatomic gas is at a pressure of \[4\times {{10}^{4}}N/{{m}^{2}}\]. The density of the gas is \[8\text{ }kg/{{m}^{3}}\]. What is the order of energy of the gas due to its thermal motion? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[{{10}^{4}}\] J
  done clear
  B)
  \[{{10}^{3}}J\]
  done clear
  C)
  \[{{10}^{5}}\text{ }J\]
  done clear
  D)
                   \[{{10}^{6}}J\]
  done clear
  View Answer play_arrow

• question_answer17) The modulation frequency of an AM radio station is 250 kHz, which is 10% of the carrier wave. If another AM station approaches you for license what broadcast frequency will you allot? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  2900 kHz                                  
  done clear
  B)
  2750 kHz
  done clear
  C)
  2250 kHz          
  done clear
  D)
                   2000 kz
  done clear
  View Answer play_arrow

• question_answer18) The electric field of a plane polarized electromagnetic wave in free space at time  \[t=0\] is given by an expression \[\overrightarrow{E}\left( x,y \right)=10\widehat{j}\text{ }cos\left[ \left( 6x+8z \right) \right]\]. The magnetic field \[\overrightarrow{B}\left( x,\text{ }z,\text{ }t \right)\] is given by - (c is the velocity of light) [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{1}{c}(6\widehat{k}+8\widehat{i})\,cos[(6x+8z-10ct)]\]
  done clear
  B)
  \[\frac{1}{c}(6\widehat{k}-8\widehat{i})\,cos[(6x+8z-10ct)]\]
  done clear
  C)
  \[\frac{1}{c}(6\widehat{k}+8\widehat{i})\,cos[(6x-8z+10ct)]\]
  done clear
  D)
  \[\frac{1}{c}(6\widehat{k}-8\widehat{i})\,cos[(6x+8z+10ct)]\]
  done clear
  View Answer play_arrow

• question_answer19) A particle starts from the origin at time \[t=0\] and moves along the positive x-axis. The graph of velocity with respect to time is shown in figure. What is the position of the particle at time\[t=5s\]? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  3 m                              
  done clear
  B)
  9 m   
  done clear
  C)
  10 m    
  done clear
  D)
                   6 m
  done clear
  View Answer play_arrow

• question_answer20) Two forces P and Q, of magnitude 2F and 3F, respectively; are at an angle 9 with each other. If the force Q is doubled, then their resultant also gets doubled. Then, the angle \[\theta \] is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[90{}^\circ \]                                      
  done clear
  B)
  \[60{}^\circ ~\]
  done clear
  C)
  \[30{}^\circ ~~\]         
  done clear
  D)
                   \[120{}^\circ \]
  done clear
  View Answer play_arrow

• question_answer21) The eye can be regarded as a single refracting surface. The radius of curvature of this surface is equal to that of cornea (7.8 mm). This surface separateds two media of refractive indices 1 and 1.34. Calculate the distance from the refracting surface at which a parallel beam of light will come to focus- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  2 cm                            
  done clear
  B)
  3.1 cm
  done clear
  C)
  4.0 cm
  done clear
  D)
                   1 cm
  done clear
  View Answer play_arrow

• question_answer22) A cylindrical plastic bottle of negligible mass is filled with 310 ml of water and left floating in a pond with still water. If pressed downward slightly and released, it starts performing simple harmonic motion at angular frequency co. If the radius of the bottle is 2.5 cm then co is close to - (density of water\[={{10}^{3}}kg/{{m}^{3}}\]). [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[2.50\text{ }rad\text{ }{{s}^{-}}^{1}\]                      
  done clear
  B)
  \[3.75\text{ }rad\text{ }{{s}^{-1}}\]
  done clear
  C)
  \[5.00\text{ }rad\text{ }{{s}^{-1}}\]     
  done clear
  D)
                   \[1.25\text{ }rad\text{ }{{s}^{-1}}\]
  done clear
  E)
                   None of these
  done clear
  View Answer play_arrow

• question_answer23) A hope and a solid cylinder of same mass and radius are made of a permanent magnetic material with their magnetic moment parallel to their respective axes. But the magnetic moment of hoop is twice of solid cylinder. They are placed in a uniform magnetic field in such a manner angle with the field. If the oscillation periods of hoop and cylinder are \[{{T}_{h}}\text{ }and\text{ }{{T}_{c}}\] respectively, then- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[{{T}_{h}}=1.5\text{ }{{T}_{c}}\]                             
  done clear
  B)
  \[{{T}_{h}}={{T}_{c}}\]
  done clear
  C)
  \[{{T}_{h}}=2{{T}_{c}}\]       
  done clear
  D)
                   \[{{T}_{h}}=0.5{{T}_{c}}\]
  done clear
  View Answer play_arrow

• question_answer24) The Wheatstone bridge shown in figure, here, gets balanced when the carbon resistor used as \[{{R}_{1}}\] has the colour code (Orange, Red, Brown).  he resistors \[{{R}_{2}}\text{ }and\text{ }{{R}_{4}}\text{ }are\text{ }80\Omega \,\,and\text{ }40\Omega \] , respectively. Assuming that the colour code for the carbon resistors gives their accurate values, the colour code for the carbon resistor, used as Rs, would be- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  Brown, Blue, Brown                   
  done clear
  B)
  Grey, Black, Brown
  done clear
  C)
  Red, Green, Brown                     
  done clear
  D)
  Brown, Blue, Black
  done clear
  View Answer play_arrow

• question_answer25) The actual value of resistance R, shown in the figure is \[30\,\Omega \]. This is measured in an experiment as shown using the standard formula \[R=\frac{V}{I}\] where V and I are the readings of the voltmeter and ammeter, respectively. If the measured value of R is \[5%\] less, then the internal resistance of the voltmeter is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  570 \[\Omega \]                         
  done clear
  B)
  600 \[\Omega \]
  done clear
  C)
  350 \[\Omega \]
  done clear
  D)
                   35 \[\Omega \]
  done clear
  View Answer play_arrow

• question_answer26) An unknown metal of mass 192 g heated to a temperature of \[100{}^\circ C\] was immersed into a brass calorimeter of mass 128 g containing 240 g of water at a temperature of \[8.4{}^\circ \,C\]. Calculate the specific heat of the unknown metal if water temperature stabilizes at \[21.5{}^\circ C\]. (Specific heat of brass is \[394\text{ }J\text{ }k{{g}^{-1}}{{K}^{-1}}\]) [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  458 J \[394\text{ }J\text{ }k{{g}^{-1}}{{K}^{-1}}\]                
  done clear
  B)
  1232 J \[394\text{ }J\text{ }k{{g}^{-1}}{{K}^{-1}}\]
  done clear
  C)
  654 J \[394\text{ }J\text{ }k{{g}^{-1}}{{K}^{-1}}\]
  done clear
  D)
                   916 J \[394\text{ }J\text{ }k{{g}^{-1}}{{K}^{-1}}\]
  done clear
  View Answer play_arrow

• question_answer27) A particle which is experiencing a force, given by \[\overrightarrow{F}=3\overrightarrow{i}-12\overrightarrow{j}\], undergoes a displacement of \[\overrightarrow{d}=4\overrightarrow{i}\] . If particle had a kinetic energy of 3 J at the beginning of the displacement what is its kinetic energy at the end of the displacement? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  9 J                               
  done clear
  B)
  10 J  
  done clear
  C)
  12 J     
  done clear
  D)
                   15 J
  done clear
  View Answer play_arrow

• question_answer28) A particle executes simple harmonic motion with an amplitude of 5 cm. When the particle is at 4 cm from the mean position, the magnitude of its velocity in SI units is equal to that of its acceleration. Then, its periodic time in seconds is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{4\pi }{3}\]                                  
  done clear
  B)
  \[\frac{3\,}{8}\pi \]
  done clear
  C)
  \[\frac{7\,}{3}\pi \]                    
  done clear
  D)
                   \[\frac{8\,\pi }{3}\]
  done clear
  View Answer play_arrow

• question_answer29) Two identical spherical balls of mass M and radius R each are stuck on two ends of a rod of length 2R and mass M (see figure). The moment of inertia of the system about the axis passing perpendicularly through the centre of the rod is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{17}{15}M{{R}^{2}}\]               
  done clear
  B)
  \[\frac{137}{15}M{{R}^{2}}\]
  done clear
  C)
  \[\frac{209}{15}M{{R}^{2}}\]
  done clear
  D)
                   \[\frac{152}{15}M{{R}^{2}}\]
  done clear
  View Answer play_arrow

• question_answer30) A   parallel   plate   capacitor   having capacitance 12 pF is charged by a battery to a potential difference of 10 V between its plates. The charging battery is now disconnected and a porcelain slab of dielectric constant 6.5 is slipped between the plates. The work done by the capacitor on the slab is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  508 pJ  
  done clear
  B)
  692 pJ
  done clear
  C)
  560 pJ  
  done clear
  D)
                   600 pJ
  done clear
  View Answer play_arrow

• question_answer31) A reaction of cobalt (III) chloride and ethylenediamine in a 1 : 2 mole ratio generates two isomeric products A (violet coloured) and B (green coloured). A can show optical activity, but B is optically inactive. What type of isomers does A and B represent? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  Ionisation isomers          
  done clear
  B)
       Linkage isomers
  done clear
  C)
  Coordination isomers                  
  done clear
  D)
  Geometrical isomers
  done clear
  View Answer play_arrow

• question_answer32) The pair that contains two \[P-H\] bonds in each of the oxoacids is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[{{H}_{3}}P{{O}_{2}}\text{ }and\text{ }{{H}_{4}}{{P}_{2}}{{O}_{5}}\]                
  done clear
  B)
  \[{{H}_{4}}{{P}_{2}}{{O}_{5}}\text{ }and\text{ }{{H}_{4}}{{P}_{2}}{{O}_{6}}\]
  done clear
  C)
  \[{{H}_{4}}{{P}_{2}}{{O}_{5}}\,and\,{{H}_{3}}P{{O}_{3}}\]                      
  done clear
  D)
  \[{{H}_{3}}P{{O}_{3}}\] and \[{{H}_{3}}P{{O}_{2}}\]
  done clear
  View Answer play_arrow

• question_answer33) In  the  reaction   of  oxalate  with permanganate in acidic medium, the number of electrons involved in producing one molecule of \[C{{O}_{2}}\] is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  10                                
  done clear
  B)
  2      
  done clear
  C)
  1                     
  done clear
  D)
                   5
  done clear
  View Answer play_arrow

• question_answer34) The reaction that is NOT involved in the ozone layer depletion mechanism in the stratosphere is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[Cl\overset{\bullet }{\mathop{O}}\,(g)+O(g)\,\,\to \,\,\overset{\bullet }{\mathop{Cl}}\,(g)+{{O}_{2}}(g)\]
  done clear
  B)
  \[C{{F}_{2}}C{{l}_{2}}(g)\,\,\,\xrightarrow{uv}\,\,\overset{\bullet }{\mathop{Cl}}\,(g)+\overset{\bullet }{\mathop{C}}\,{{F}_{2}}Cl(g)\]
  done clear
  C)
  \[\,C{{H}_{4}}+2{{O}_{3}}\to 3C{{H}_{2}}=O+3\,\,{{H}_{2}}O\]
  done clear
  D)
  \[HOCl(g)\xrightarrow{hv}\,\,\overset{\bullet }{\mathop{OH}}\,\,(g)+\overset{\bullet }{\mathop{Cl\,}}\,(g)\]
  done clear
  View Answer play_arrow

• question_answer35) An aromatic compound 'A' having molecular formula \[{{C}_{7}}{{H}_{6}}{{O}_{2}}\] on treating with aqueous ammonia and heating forms compound 'B'. The compound 'B' on reaction with molecular bromine and potassium hydroxide provides compound 'C' having molecular formula\[{{C}_{6}}{{H}_{7}}N\]. The structure of 'A' is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
             
  done clear
  B)
  
  done clear
  C)
     
  done clear
  D)
  
  done clear
  View Answer play_arrow

• question_answer36) For an elementary chemical reaction; \[{{A}_{2}}\,\,2{{A}_{1}}\], the expression for \[\frac{d[A]}{dt}\] is [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[2{{K}_{1}}\left[ {{A}_{2}} \right]-{{K}_{-1}}{{[A]}^{2}}\]               
  done clear
  B)
  \[{{K}_{1}}\left[ {{A}_{2}} \right]-{{K}_{-1}}{{[A]}^{2}}\]
  done clear
  C)
  \[{{K}_{1}}\left[ {{A}_{2}} \right]+{{K}_{-1}}{{[A]}^{2}}\]
  done clear
  D)
                   \[2{{K}_{1}}\left[ {{A}_{2}} \right]-2{{K}_{-1}}{{[A]}^{2}}\]
  done clear
  View Answer play_arrow

• question_answer37) The electrolytes usually used in the electroplating   of gold and silver, respectively are: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[{{\left[ Au{{\left( CN \right)}_{2}} \right]}^{-}}and\text{ }{{\left[ Ag{{\left( CN \right)}_{2}} \right]}^{-}}\]
  done clear
  B)
  \[{{\left[ Au{{\left( CN \right)}_{2}} \right]}^{-}}and\text{ }{{\left[ Ag{{\left( Cl \right)}_{2}} \right]}^{-}}\]
  done clear
  C)
  \[{{\left[ Au{{\left( OH \right)}_{4}} \right]}^{-}}and\text{ }{{\left[ Ag{{\left( OH \right)}_{2}} \right]}^{-}}\]
  done clear
  D)
  \[{{[Au{{(N{{H}_{3}})}_{2}}]}^{+}}\,and\,\,{{[Ag{{(CN)}_{2}}]}^{-}}\]
  done clear
  View Answer play_arrow

• question_answer38) Among the following reactions of hydrogen with halogens, the one that requires a catalyst is [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[{{H}_{2}}+B{{r}_{2}}\to 2HBr\]                  
  done clear
  B)
  \[{{H}_{2}}+C{{l}_{2}}\to 2HCl\]
  done clear
  C)
  \[{{H}_{2}}+{{F}_{2}}\to 2HF\]                     
  done clear
  D)
  \[{{H}_{2}}+{{I}_{2}}\to 2HI\]
  done clear
  View Answer play_arrow

• question_answer39) The major product of the following reaction is [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
                       
  done clear
  B)
  
  done clear
  C)
                    
  done clear
  D)
  
  done clear
  View Answer play_arrow

• question_answer40) What is the IUPAC name of the following compound?   [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  4-Bromo-3-methylpent-2-ene
  done clear
  B)
  3-Bromo 1, 2-dimethylbut-1-ene
  done clear
  C)
  3-Bromo-3-methyl-1, 2-dimethylprop-1-ene
  done clear
  D)
  2-Bromo-3-methylpent-3-ene
  done clear
  View Answer play_arrow

• question_answer41) A compound of formula \[{{A}_{2}}{{B}_{3}}\] has the hcp lattice. Which atom forms the hcp lattice and what fraction of tetrahedral voids is occupied by the other atoms: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  hcp lattice - A, \[\frac{1}{3}\] Tetrahedral voids - B
  done clear
  B)
  hcp lattice - B, \[\frac{1}{3}\] Tetrahedral voids - A
  done clear
  C)
  hcp lattice - A, \[\frac{2}{3}\] Tetrahedral voids - B
  done clear
  D)
  hcp lattice -B, \[\frac{2}{3}\] Tetrahedral voids - A
  done clear
  View Answer play_arrow

• question_answer42) Sodium metal on dissolution in liquid ammonia gives a deep blue solution due to the formation of: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  ammoniated electrons
  done clear
  B)
  sodamide
  done clear
  C)
  sodium-ammonia complex
  done clear
  D)
  sodium ion-ammonia complex
  done clear
  View Answer play_arrow

• question_answer43) Which of the following- test cannot be used for identifying amino acids? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  Ninhydrin test                
  done clear
  B)
  Barfoed lest
  done clear
  C)
  Xanthoproteic test                      
  done clear
  D)
  Biuret test
  done clear
  View Answer play_arrow

• question_answer44) What will be the major product in the following mononitration reaction? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
                        
  done clear
  B)
   
  done clear
  C)
                         
  done clear
  D)
  
  done clear
  View Answer play_arrow

• question_answer45) The difference in the number of unpaired electrons of a metal ion in its high spin and low-spin octahedral complexes is two. The metal ion is [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[M{{n}^{2+}}\]                                
  done clear
  B)
  \[N{{i}^{2}}^{+}\]  
  done clear
  C)
  \[C{{o}^{2+}}\]         
  done clear
  D)
                   \[F{{e}^{2}}^{+}\]
  done clear
  View Answer play_arrow

• question_answer46) The ground state energy of hydrogen atom is- 13.6 eV. The energy of second excited state of \[H{{e}^{+}}\] ion in eV is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  - 6.04
  done clear
  B)
                               - 54.4
  done clear
  C)
  - 27.2   
  done clear
  D)
                   - 3.4
  done clear
  View Answer play_arrow

• question_answer47) The 71st electron of an element X with an atomic  number of 71 enters into the orbital; [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  4f                                
  done clear
  B)
  6s    
  done clear
  C)
  6p        
  done clear
  D)
                   5d
  done clear
  View Answer play_arrow

• question_answer48) The major product of the following reaction [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
               
  done clear
  B)
  
  done clear
  C)
        
  done clear
  D)
                  
  done clear
  View Answer play_arrow

• question_answer49) The major product obtained in the following reaction is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
     
  done clear
  B)
   
  done clear
  C)
                    
  done clear
  D)
  
  done clear
  View Answer play_arrow

• question_answer50)   In the cell \[Pt\left| \,\left( s \right)\, \right|{{H}_{2}}\](g, 1 bar) \[\left| \text{ }HCl\left( aq \right)\text{ } \right|\] \[AgCl\left| \,\left( s \right)\, \right|\,Ag\left( s \right)|Pt\left( s \right)\] the cell potential is 0.92 V when a \[{{10}^{-}}^{6}\] molal HCl solution is used. The standard electrode potential of \[\left( AgCl/Ag,C{{l}^{-}} \right)\] electrode is: {Given, \[\frac{2.303RT}{F}\,=\,0.06V\,at\,\,298\,K\] [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  0.94 V                          
  done clear
  B)
  0.40V
  done clear
  C)
  0.76 V  
  done clear
  D)
                   0.20 V
  done clear
  View Answer play_arrow

• question_answer51) Which is the most suitable reagent for the following transformation? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  alkaline\[KMn{{O}_{4}}\]                      
  done clear
  B)
  Tollen's neagent
  done clear
  C)
  \[{{I}_{2}}/NaOH\]      
  done clear
  D)
  \[Cr{{O}_{2}}C{{l}_{2}}/C{{S}_{2}}\]
  done clear
  View Answer play_arrow

• question_answer52) The process with negative entropy change is [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  Dissociation of\[CaS{{O}_{4}}\], (s) to CaO(s) and \[S{{O}_{3}}\](g)
  done clear
  B)
  Dissolution of iodine in water
  done clear
  C)
  Synthesis of ammonia from N2 and H2
  done clear
  D)
  Sublimation of dry ice
  done clear
  View Answer play_arrow

• question_answer53) Elevation in the boiling point for 1 molar solution of glucose is 2 K. The depression in the freezing point for 2 molar solution of glucose in the same solvent is 2 K. The relation between \[{{K}_{b}}\] and \[{{K}_{f}}\] is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[{{K}_{b}}={{K}_{f}}\]                                 
  done clear
  B)
  \[{{K}_{b}}\,=0.5\,\,{{K}_{f}}\]
  done clear
  C)
  \[{{K}_{b}}\,=\,1.5\,{{K}_{f}}\]           
  done clear
  D)
                   \[{{K}_{b}}=2\,\,{{K}_{f}}\]
  done clear
  View Answer play_arrow

• question_answer54) The amount of sugar \[\left( {{C}_{12}}{{H}_{22}}{{O}_{11}} \right)\] required to prepare 2L of its 0.1 M aqueous solution is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  17.1 g                          
  done clear
  B)
  34.2 g
  done clear
  C)
  68.4 g  
  done clear
  D)
                   136.8 g
  done clear
  View Answer play_arrow

• question_answer55) The correct match between item - I and item - II is:

  Item - I (compound)	Item - II (reagent)
  (A) Lysine	(P) 1-naphthol
  (B) Furfural	(Q) ninhydrin
  (C) Benzylalcohol	(R) \[KMn{{O}_{4}}\]
  (D) Styrene	(S) Ceric ammonium nitate

   [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  [A] \[\to \] (Q); [B] \[\to \] (R); [C] \[\to \] (S); [D] \[\to \] (P)
  done clear
  B)
  [A] \[\to \] (Q); [B] \[\to \] (P); [C] \[\to \] (S); [D] \[\to \] (R)
  done clear
  C)
  [A] \[\to \]  (R); [B] \[\to \] (P); [C] \[\to \] (Q); [D] \[\to \] (S)
  done clear
  D)
  [A] \[\to \] (Q); [B] \[\to \] (P); [C] \[\to \] (R); [D] \[\to \] (S)
  done clear
  View Answer play_arrow

• question_answer56) An ideal gas undergoes isothermal compression from \[5{{m}^{3}}\] to \[1\text{ }{{m}^{3}}\] against a constant external pressure of \[4\text{ }N{{m}^{-}}^{2}\]. Heat released in this process is used to increase the temperature of 1 mole of Al. If molar heat capacity of Al is 24 J \[mo{{l}^{-1}}\text{ }{{K}^{-1}}\], the temperature of Al increases by: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{2}{3}\]K                                    
  done clear
  B)
  \[\frac{3}{2}\]K   
  done clear
  C)
  1 K                  
  done clear
  D)
                   2 K
  done clear
  View Answer play_arrow

• question_answer57) The major product of the following reaction is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  
  done clear
  B)
  
  done clear
  C)
  
  done clear
  D)
  
  done clear
  View Answer play_arrow

• question_answer58) The number of 2-centre-2-electron and 3- centre   -2-electron bonds in \[{{B}_{2}}{{H}_{6}}\], respectively are: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  2 and 2                        
  done clear
  B)
  2 and 1
  done clear
  C)
  2 and 4
  done clear
  D)
                   4 and 2
  done clear
  View Answer play_arrow

• question_answer59) Haemoglobin and gold sol are examples of: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  positively charged sols
  done clear
  B)
  negatively charged sols
  done clear
  C)
  Positively and negatively charged sols, respectively
  done clear
  D)
  negatively and positively charged sols, respectively
  done clear
  View Answer play_arrow

• question_answer60) 5.1 g \[N{{H}_{4}}SH\] is introduced in 3.0 L evacuated flask at \[327{}^\circ C\]. 30% of the solid \[N{{H}_{4}}SH\] decomposed to \[N{{H}_{3}}\] and \[{{H}_{2}}S\] as gases. The \[{{K}_{p}}\] of the reaction at \[327{}^\circ C\] is (\[R=0.082\] L atm \[mo{{l}^{-1}}\text{ }{{K}^{-}}^{1}\], Molar mass of \[S=32\] g \[mo{{l}^{-}}^{1}\] molar mass of \[N=14\,g\text{ }mo{{l}^{-1}}\]) [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[0.242\times {{10}^{-4}}\text{ }at{{m}^{2}}\]                      
  done clear
  B)
  \[1\times {{10}^{-4}}\text{ }at{{m}^{2}}\]
  done clear
  C)
  \[4.9\times {{10}^{-3}}\text{ }at{{m}^{2}}\]
  done clear
  D)
                   \[0.242\text{ }at{{m}^{2}}\]
  done clear
  View Answer play_arrow

• question_answer61) The length of the chord of the parabola \[{{x}^{2}}=4y\] having equation \[x-\sqrt{2}y+4\sqrt{2}=0\] is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[8\sqrt{2}\]
  done clear
  B)
                               \[6\sqrt{3}\]
  done clear
  C)
  \[3\sqrt{2}\]      
  done clear
  D)
                   \[2\sqrt{11}\]
  done clear
  View Answer play_arrow

• question_answer62) Let N be the set of natural numbers and two functions f and g be defined as \[f,\text{ }g\text{ }:\text{ }N\to N\] such that \[f(n)\,=\,\left\{ \begin{matrix}    \frac{n+1}{2}  \\    \frac{n}{2}  \\ \end{matrix} \right.\,\,\,\begin{matrix}    ;\,\,\,\,if\,\,n\,\,is\,\,odd  \\    ;\,\,if\,\,n\,\,is\,\,given  \\ \end{matrix}\,\,\,\,;\,\,and\]\[g\left( n \right)=n-{{\left( -1 \right)}^{n}}\] . Then fog is [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  neither one-one nor onto
  done clear
  B)
  onto but not one-one
  done clear
  C)
  both one-one and onto
  done clear
  D)
  one-one but not onto
  done clear
  View Answer play_arrow

• question_answer63) Two sides of a parallelogram are along the lines,\[x+y=3\,\,\,\And \,\,x-y+3=0\]. If its diagonals intersect at (2, 4), then one of its vertex is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  (2, 1)                            
  done clear
  B)
  (2, 6) 
  done clear
  C)
  (3, 5)    
  done clear
  D)
                   (3, 6)
  done clear
  View Answer play_arrow

• question_answer64) If mean and standard deviation of 5 observations \[{{x}_{1}},\text{ }{{x}_{2}},\text{ }{{x}_{3}},\text{ }{{x}_{4}},\text{ }{{x}_{5}}\] are 10 and 3 respectively, then the variance of 6 observations \[{{x}_{1}},\text{ }{{x}_{2}},\text{ }......\text{ }{{x}_{5}}\] and - 50 is equal to [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  582.5                           
  done clear
  B)
  507.5
  done clear
  C)
  586.5   
  done clear
  D)
                   509.5
  done clear
  View Answer play_arrow

• question_answer65) The value of cot \[\left( \sum\limits_{n\,=\,1}^{19}{{{\cot }^{-1}}}\left( 1+\sum\limits_{p\,=\,1}^{n}{2\,p} \right) \right)\]is - [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{22}{23}\]                                               
  done clear
  B)
  \[\frac{23}{22}\]
  done clear
  C)
  \[\frac{21}{19}\]                       
  done clear
  D)
                   \[\frac{19}{21}\]
  done clear
  View Answer play_arrow

• question_answer66) The value of\[cos\frac{\pi }{{{2}^{2}}}.\,cos\frac{\pi }{{{2}^{3}}}\,\,......\,cos\,\frac{\pi }{{{2}^{10}}}.\,sin\,\frac{\pi }{{{2}^{10}}}\] is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{1}{256}\]                                   
  done clear
  B)
  \[\frac{1}{2}\]
  done clear
  C)
  \[\frac{1}{1024}\]         
  done clear
  D)
                   \[\frac{1}{512}\]
  done clear
  View Answer play_arrow

• question_answer67) If \[\sum\limits_{r\,=\,0}^{25}{{{\{}^{50}}{{C}_{r}}{{.}^{50\,-\,r}}{{C}_{25\,-\,r}}\}\,=\,K{{(}^{50}}{{C}_{25}})}\] then K is equal to [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[{{2}^{24}}\]                        
  done clear
  B)
  \[{{2}^{25}}-1\]
  done clear
  C)
  \[{{2}^{25}}\]            
  done clear
  D)
                   \[{{\left( 25 \right)}^{2}}\]
  done clear
  View Answer play_arrow

• question_answer68) Let \[{{a}_{1}},\text{ }{{a}_{2}},{{a}_{3}},.....\text{ }{{a}_{10}}\] be in G.P. with \[{{a}_{i}}>0\] for \[i=1,\text{ }2,\text{ }......10\] and S be the set of pairs (r, k), r, k e N (the set of natural numbers) for which

  \[\left| \begin{matrix}    {{\log }_{e}}\,{{a}_{1}}{{\,}^{r}}{{a}_{2}}^{k} & {{\log }_{e}}\,{{a}_{2}}{{\,}^{r}}{{a}_{3}}^{k} & {{\log }_{e}}\,{{a}_{3}}{{\,}^{r}}{{a}_{4}}^{k}  \\    {{\log }_{e}}\,{{a}_{4}}{{\,}^{r}}{{a}_{5}}^{k} & {{\log }_{e}}\,{{a}_{5}}{{\,}^{r}}{{a}_{6}}^{k} & {{\log }_{e}}\,{{a}_{6}}{{\,}^{r}}{{a}_{7}}^{k}  \\    {{\log }_{e}}\,{{a}_{7}}{{\,}^{r}}{{a}_{8}}^{k} & {{\log }_{e}}\,{{a}_{8}}{{\,}^{r}}{{a}_{9}}^{k} & {{\log }_{e}}\,{{a}_{9}}{{\,}^{r}}{{a}_{10}}^{k}  \\ \end{matrix} \right|=0\]

  Then the number of elements in S, is -

    [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  10                                            
  done clear
  B)
  4
  done clear
  C)
  2                     
  done clear
  D)
                   infinitely many
  done clear
  View Answer play_arrow

• question_answer69) Two vertices of a triangle are (0, 2) and (4, 3). If its orthocenter is at the origin,  then its third vertex lies in which quadrant- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  third                             
  done clear
  B)
  fourth
  done clear
  C)
  second  
  done clear
  D)
                   first
  done clear
  View Answer play_arrow

• question_answer70) If the probability of hitting a target by a shooter, in any shot, is \[\frac{1}{3}\], then the minimum number of independent shots at the target required by him so that the probability of hitting the target at least once is greater than \[\frac{5}{6}\], is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  4                                             
  done clear
  B)
  6      
  done clear
  C)
  5                     
  done clear
  D)
                   3
  done clear
  View Answer play_arrow

• question_answer71) The tangent to the curve, \[y=x{{e}^{{{x}^{2}}}}\]passing through the point (1, e) also passes through the point
  A)
  \[\left( \frac{4}{3},\,\,\,2e \right)\]                        
  done clear
  B)
  \[\left( 3,\,\,\,6e \right)\]
  done clear
  C)
  \[\left( 2,\,\,3e \right)\]     
  done clear
  D)
                   \[\left( \frac{5}{3},\,\,2e \right)\]
  done clear
  View Answer play_arrow

• question_answer72) The value of \[\int\limits_{-\pi /2}^{\pi /2}{\frac{dx}{[x]+[sin\,x]+4}}\] where [t] denotes the greatest integer less than or equal to t, is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{1}{12}(7\pi -5)\]                          
  done clear
  B)
  \[\frac{1}{12}(7\pi +5)\]
  done clear
  C)
  \[\frac{3}{10}(4\pi -3)\]  
  done clear
  D)
                   \[\frac{3}{20}(4\pi -3)\]
  done clear
  View Answer play_arrow

• question_answer73) Let \[S=\,\left\{ (x,\,\,y)\,\in \,\,{{R}^{2}}:\frac{{{y}^{2}}}{1+r}-\frac{{{x}^{2}}}{1-r}=1 \right\};\,r\ne \pm 1\]Then S represents [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  an ellipse whose eccentricity is \[\frac{1}{\sqrt{r}+1}\] where \[r>1\]
  done clear
  B)
  a hyperbola whose eccentricity is \[\frac{2}{\sqrt{r+1}}\], when \[0<r<1\]
  done clear
  C)
  a hyperbola whose eccentricity is \[\frac{2}{\sqrt{1-r}}\]when \[0<r<1\]
  done clear
  D)
  an ellipse whose eccentricity is \[\sqrt{\frac{2}{r+1}}\] when  \[r>1\]
  done clear
  View Answer play_arrow

• question_answer74) If \[\int\limits_{0}^{x}{f(t)\,dt\,\,=\,\,{{x}^{2}}+}\int\limits_{x}^{1}{{{t}^{2}}f(t)\,\,dt\,\,then\,\,f\,\,'\left( \frac{1}{2} \right)}\] is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{18}{25}\]                                               
  done clear
  B)
  \[\frac{6}{25}\]
  done clear
  C)
  \[\frac{24}{25}\]                       
  done clear
  D)
                   \[\frac{4}{5}\]
  done clear
  View Answer play_arrow

• question_answer75) Let \[A=\left[ \begin{matrix}    2 & b & 1  \\    b & {{b}^{2}}+1 & b  \\    1 & b & 2  \\ \end{matrix} \right]\] where\[b>0\]. Then the minimum value of \[\frac{\det (A)}{b}\]is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\sqrt{3}\]                                
  done clear
  B)
  \[-2\sqrt{3}\]
  done clear
  C)
  \[-\sqrt{3}\]       
  done clear
  D)
                   \[2\sqrt{3}\]
  done clear
  View Answer play_arrow

• question_answer76) With the usual notation, in \[\Delta \,ABC\], if \[\angle A+\angle B=120{}^\circ \], \[a=\sqrt{3}+1\,\,and\,\,b=\sqrt{3}-1\], then the ratio \[\angle A:\angle B\], is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  9 : 7                             
  done clear
  B)
  7 : 1  
  done clear
  C)
  5 : 3                 
  done clear
  D)
                   3 : 1
  done clear
  View Answer play_arrow

• question_answer77) The value of \[\lambda \]. such that sum of the squares of the roots of the quadratic equation, \[{{x}^{2}}+(3-\lambda )x+2=\lambda \] has the least value is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  1                                 
  done clear
  B)
  2     
  done clear
  C)
  \[\frac{15}{8}\]             
  done clear
  D)
                   \[\frac{4}{9}\]
  done clear
  View Answer play_arrow

• question_answer78) On which of the following lines lies the point  of intersection of the line, \[\frac{x-4}{2}=\frac{y-5}{2}=\frac{z-3}{1}\] and the plane,\[x+y+z=2\]? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{x-4}{1}=\frac{y-5}{1}=\frac{z-5}{-1}\]
  done clear
  B)
  \[\frac{x-2}{2}=\frac{y-3}{2}=\frac{z+3}{3}\]
  done clear
  C)
  \[\frac{x-1}{1}=\frac{y-3}{2}=\frac{z+4}{-5}\]
  done clear
  D)
  \[\frac{x+3}{3}=\frac{4-y}{3}=\frac{z+1}{-\,2}\]
  done clear
  View Answer play_arrow

• question_answer79) The positive value of \[\lambda \] for which the co-efficient of \[{{x}^{2}}\] in the expression \[{{x}^{2}}{{\left( \sqrt{x}+\frac{\lambda }{{{x}^{2}}} \right)}^{10}}\]is 720, is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  4                                 
  done clear
  B)
  \[2\sqrt{2}\]
  done clear
  C)
  3                     
  done clear
  D)
                   \[\sqrt{5}\]
  done clear
  View Answer play_arrow

• question_answer80) Let \[z={{\left( \frac{\sqrt{3}}{2}+\frac{i}{2} \right)}^{5}}\,+\,{{\left( \frac{\sqrt{3}}{2}-\frac{i}{2} \right)}^{5}}\]. If R(z) and I(z) respectively denote the real and imaginary parts of z, then- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[R\left( z \right)=-3\]
  done clear
  B)
  \[R\left( z \right)<0\text{ }and\text{ }I\left( z \right)>0\]
  done clear
  C)
  \[I\left( z \right)=0\]
  done clear
  D)
  \[R\left( z \right)>0\text{ }and\text{ }I\left( z \right)>0\]
  done clear
  View Answer play_arrow

• question_answer81) The number of values of \[\theta \,\in (0,\,\,\,\pi )\] for which the system of linear equations

  \[x+3y+7z=0\] \[-x+4y+7z=0\] \[\left( sin3\theta  \right)x+\left( cos2\theta  \right)y+2z=0\]

  has a non-trivial solution, is-

    [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  two                              
  done clear
  B)
  one  
  done clear
  C)
  four                              
  done clear
  D)
       three
  done clear
  View Answer play_arrow

• question_answer82) The curve amongst the family of curves represented by the differential equation, \[({{x}^{2}}-{{y}^{2}})dx+2xy\,\,\,dy=0\] which passes through (1, 1) is [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  a circle with centre on the y-axis
  done clear
  B)
  an ellipse with major axis along the y-axis
  done clear
  C)
  a circle with centre on the x-axis
  done clear
  D)
  a hyperbola with transverse axis along the x-axis
  done clear
  View Answer play_arrow

• question_answer83) Let \[f:\left( -1,\text{ }\,1 \right)\to R\] be a function defined by\[f(x)=max\left\{ -|x|-\sqrt{1-{{x}^{2}}} \right\}\]. If K be the set of all points at which f is not differentiable then K has exactly- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  one element                              
  done clear
  B)
  three elements
  done clear
  C)
  five elements     
  done clear
  D)
                   two elements
  done clear
  View Answer play_arrow

• question_answer84) Consider the following three statements:

  P : 5 is a prime number

  Q : 7  is a factor of 192

  R : L.C.M. of 5 and 7 is 35

  Then the truth value of which one of the following statements is true? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[(P\wedge Q)\vee (\sim R)\]               
  done clear
  B)
  \[P\vee (\sim Q\wedge R)\]
  done clear
  C)
  \[(\sim P)\wedge (\sim Q\wedge R)\]
  done clear
  D)
                   \[\left( \sim P \right)\vee \left( Q\wedge R \right)\]
  done clear
  View Answer play_arrow

• question_answer85) Let f be a differentiable function such that \[f'(x)\,=\,7-\frac{3}{4}\,\frac{f(x)}{x},\,\,(x>0)\] and\[f(1)\,\ne \,4\]. Then \[\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,\,xf\left( \frac{1}{x} \right)\,\] [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  does not exist                
  done clear
  B)
  exists and equals \[\frac{4}{7}\]
  done clear
  C)
  exists and equals 4                     
  done clear
  D)
  exists and equals 0
  done clear
  View Answer play_arrow

• question_answer86) If \[\overrightarrow{\alpha }=(\lambda -2)\overrightarrow{a}+\overrightarrow{b}\,\,and\,\,\overrightarrow{\beta }=(4\lambda -2)\overrightarrow{a}+3\overrightarrow{b}\] be two given vectors where vectors \[\overrightarrow{a}\] and \[\overrightarrow{b}\] are non-collinear. The value of \[\lambda \] which vectors \[\overrightarrow{a}\] and \[\overrightarrow{b}\] are collinear, is- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  4                                             
  done clear
  B)
  3     
  done clear
  C)
  - 3       
  done clear
  D)
                   - 4
  done clear
  View Answer play_arrow

• question_answer87) The plane which bisects the line segment joining the points (-3, -3, 4) and (3, 7, 6) at right angles, passes through which one of the following points? [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  (2, 1, 3)                        
  done clear
  B)
  (4, -1, 2)
  done clear
  C)
  (4, 1, -2)           
  done clear
  D)
                   (-2, 3, 5)
  done clear
  View Answer play_arrow

• question_answer88) If the area of an equilateral triangle inscribed in the circle \[{{x}^{2}}+{{y}^{2}}+10x+12y+c=0\] is \[27\sqrt{3}\] sq units then c is equal to [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  20                                
  done clear
  B)
  25    
  done clear
  C)
  -25       
  done clear
  D)
                   13
  done clear
  View Answer play_arrow

• question_answer89) If \[\int{{{x}^{5}}.\,{{e}^{-}}^{4{{x}^{3}}}dx=\frac{1}{48}{{e}^{-4{{x}^{3}}}}\,f(x)+C}\], where C is a constant of integration, then f(x) is equal to- [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[-2{{x}^{3}}-1\]                                
  done clear
  B)
  \[-\text{ }2{{x}^{3}}+1\]
  done clear
  C)
  \[4{{x}^{3}}+1\]        
  done clear
  D)
                   \[-\,4{{x}^{3}}-1\]
  done clear
  View Answer play_arrow

• question_answer90) A helicopter is flying along the curve given by\[y-{{x}^{3/2}}\,=7,\,\,(x\ge 0)\,\].   A soldier positioned at the point \[\left( \frac{1}{2},\,\,7 \right)\]wants to shoot down the helicopter when it is nearest to him. Then this nearest distance is: [JEE Main Online Paper (Held On 10-Jan-2019 Evening]
  A)
  \[\frac{1}{6}\,\sqrt{\frac{7}{3}}\]                                  
  done clear
  B)
  \[\frac{\sqrt{5}}{6}\]
  done clear
  C)
  \[\frac{1}{2}\]              
  done clear
  D)
                   \[\frac{1}{3}\,\sqrt{\frac{7}{3}}\]
  done clear
  View Answer play_arrow