List of top Questions asked in JEE Main

An object of mass 5 kg is thrown vertically upwards from the ground. The air resistance produces a constant retarding force of 10 N throughout the motion. The ratio of time of ascent to the time of descent will be equal to [Use \(g\) = \(10 \;ms^{–2}\)].
A fly wheel is accelerated uniformly from rest and rotates through 5 rad in the first second. The angle rotated by the fly wheel in the next second, will be:
A 100 g of iron nail is hit by a \(1.5\) \(kg\) hammer striking at a velocity of \(60 \;ms^{–1}\). What will be the rise in the temperature of the nail if one fourth of energy of the hammer goes into heating the nail?
[Specific heat capacity of iron = \(0.42\; Jg^{–1} °C^{–1}\)]

A boy ties a stone of mass 100 g to the end of a 2 m long string and whirls it around in a horizontal plane. The string can withstand the maximum tension of 80 N.If the maximum speed with which the stone can revolve is k/π rev./min.The value of K is(Assume the string is massless and unstretchable)

If the charge on a capacitor is increased by 2 C, the energy stored in it increases by 44%. The original charge on the capacitor is (in C)
 A vertical electric field of magnitude 4.9 × 105 N/C just prevents a water droplet of a mass of 0.1 g from falling. The value charge on the droplet will be(Given g = 9.8 m/s2)
A long cylindrical volume contains a uniformly distributed charge of density ρ. The radius of cylindrical volume is R. A charge particle (q) revolves around the cylinder in a circular path. The kinetic energy of the particle is:
A particle experiences a variable force F=(4x\(\hat i\)+3y2\(\hat j\)) in a horizontal x–y plane. Assume distance in meters and force is Newton.If the particle moves from point (1, 2) to point (2, 3) in the x–y plane; then Kinetic Energy changes by
An electric bulb is rated as 200 W. What will be the peak magnetic field at 4 m distance produced by the radiations coming from this bulb? Consider this bulb as a point source with 3.5% efficiency.
The light of two different frequencies whose photons have energies 3.8 eV and 1.4 eV respectively, illuminate a metallic surface whose work function is 0.6 eV successively. The ratio of maximum speeds of emitted electrons for the two frequencies respectively will be
Two light beams of intensities in the ratio of 9 : 4 are allowed to interfere. The ratio of the intensity of maxima and minima will be:
In Bohr’s atomic model of hydrogen, let K, P and E are the kinetic energy, potential energy and total energy of the electron respectively. Choose the correct option when the electron undergoes transitions to a higher level:
The equations of two waves are given by : 
y1 = 5 sin 2π(x – vt) cm
y2 = 3 sin 2π(x – vt + 1.5) cm
These waves are simultaneously passing through a string. The amplitude of the resulting wave is :
The approximate height from the surface of the earth at which the weight of the body becomes \(\frac{1}{3}\) of its weight on the surface of earth is [Radius of earth R = 6400 km and √3=1.732]

A resistance of 40 Ω is connected to a source of alternating current rated 220 V, 50 Hz. Find the time taken by the current to change from its maximum value to the rms value :

A plane of electromagnetic waves travels in a medium with a relative permeability of 1.61 and relative permittivity of 6.44. If the magnitude of magnetic intensity is 4.5 × 10–2 Am–1 at a point, what will be the approximate magnitude of electric field intensity?(Given: Permeability of free space μ0 = 4π × 10–7 NA–2, speed of light in vacuum c = 3 × 108 ms–1)

Choose the correct option from the following options given below :

Nucleus A is having mass number 220 and its binding energy per nucleon is 5.6 MeV. It splits in two fragments ‘B’ and ‘C’ of mass numbers 105 and 115. The binding energy of nucleons in ‘B’ and ‘C’ is 6.4 MeV per nucleon. The energy Q released per fission will be :

\(120 \;g\) of an organic compound that contains only carbon and hydrogen gives \(330\) \(g\) of \(CO_2\) and \(270\) \(g\) of water on complete combustion. The percentage of carbon and hydrogen, respectively are
The energy of one mole of photons of radiation of wavelength \(300\) \(nm\) is (Given \(h\) = \(6.63 × 10^{–34}\)Js, \(N_A\) = \(6.02 × 10^{23}\) \(mol^{–1}\), \(c = 3 × 10^8\) \(ms^{–1}\))
The correct order of bond orders of \(C_2^{2-}, N_2^{2-}, O_2^{2-}\) is, respectively
At 25°C and 1 atm pressure,the enthalpies of combustion are as given below:
\(Substance\)\(H_2\)\(C(graphite)\)\(C_2H_6(g)\)
\(\frac{D_cH^{\theta}}{kJmol^{-1}}\)\(-286.0\)\(-394.0\)-1560.0

The enthalpy of formation of ethane is

For a first order reaction, the time required for completion of 90% reaction is ‘x’ times the half life of the reaction. The value of ‘x’ is (Given: In 10 = 2.303 and log 2 = 0.3010)
Metals generally melt at very high temperature. Amongst the following, the metal with the highest melting point will be
Which of the following chemical reactions represents Hall-Heroult Process?