List of top Questions asked in JEE Main

A block of mass 200 g is kept stationary on a smooth inclined plane by applying a minimum horizontal force  \(F=\sqrt xN\) as shown in figure. 
The value of x = ______.
A heat engine operates with the cold reservoir at temperature 324 K. The minimum temperature of the hot reservoir, if the heat engine takes 300 J heat from the hot reservoir and delivers 180 J heat to the cold reservoir per cycle, is _____ K.
A set of 20 tuning forks is arranged in a series of increasing frequencies. If each fork gives 4 beats with respect to the preceding fork and the frequency of the last fork is twice the frequency of the first, then the frequency of last fork is _______ Hz
Two 10 cm long, straight wires, each carrying a current of 5 A are kept parallel to each other. If each wire experienced a force of 10–5 N, then separation between the wires is _____ cm.
A small bulb is placed at the bottom of a tank containing water to a depth of √7 m. The refractive index of water is 4/3. The area of the surface of water through which light from the bulb can emerge out is xπ m2. The value of x is ________.
A travelling microscope is used to determine the refractive index of a glass slab. If 40 divisions are there in 1 cm on main scale and 50 Vernier scale divisions are equal to 49 main scale divisions, then least count of the travelling microscope is _______× 10–6 m.
The stopping potential for photoelectrons emitted from a surface illuminated by light of wavelength 6630 Å is 0.42 V. If the threshold frequency is x × 1013/s, where x is ____ (nearest integer).
(Given, speed of light = 3 × 108 m/s, Planck’s constant = 6.63 × 10–34 Js)

CNG is an important transportation fuel. When 100 g CNG is mixed with 208 g oxygen in vehicles, it leads to the formation of CO2 and H2O and produced large quantity of heat during this combustion, then the amount of carbon dioxide, produced in grams is _____. [nearest integer]
 [Assume CNG to be methane]

In a solid AB, A atoms are in ccp arrangement and B atoms occupy all the octahedral sites. If two atoms from the opposite faces are removed, then the resultant stoichiometry of the compound is AxBy. The value of x is _____. [nearest integer]
Amongst SF4, XeF4, CF4 and H2O, the number of species with two lone pair of electrons is _____.
The osmotic pressure exerted by a solution prepared by dissolving 2.0 g of protein of molar mass 60 kg mol–1 in 200 mL of water at 27°C is _________ Pa. [Integer value]
(use R = 0.083 L bar mol–1 K–1)
Let \(g : (0, ∞) →R\) be a differentiable function such that \(∫(\frac {x(cos⁡x−sin⁡x)}{e^x+1} + \frac {g(x)(e^x+1−xe^x)}{(e^x+1)2})dx = \frac {xg(x)}{e^x+1}+c,\) for all \(x>0\), where c is an arbitrary constant. Then:
40% of HI undergoes decomposition to H2 and I2 at 300 K. ΔG° for this decomposition reaction at one atmosphere pressure is _____ J mol–1. [nearest integer]
(Use R = 8.31 J K–1 mol–1; log 2 = 0.3010, ln 10 = 2.3, log 3 = 0.477)

\(Cu(S)+Sn^{2+} (0.001M) Cu^{2+} (0.01M) + Sn(s)\)
The Gibbs free energy change for the above reaction at 298 K is x × 10-1 × kJ mol-1. The value of x is ________ .[nearest integer]
[Given \(E^{-}_{cu^{2+} / cu} = 0.34V; E^{-}_{Sn^{2+} / Sn} = - 0.14V; F = 96500 C ∼ mol^{-1}\)]

Moment of Inertia (M.I.) of four bodies having same mass ‘M‘ and radius ‘2R‘ are as follows:

I1 = M.I. of solid sphere about its diameter

I2 = M.I. of solid cylinder about its axis

I3 = M.I. of solid circular disc about its diameter.

I4 = M.I. of thin circular ring about its diameter

If 2(I2 + I3) + I4 = x⋅ I1 then the value of x will be ______.

Two satellites S1 and S2 are revolving in circular orbits around a planet with radius R1 = 3200 km and R2 = 800 km respectively. The ratio of speed of satellite S1 to the speed of satellite S2 in their respective orbits would be 1/x where x =

Catalyst A reduces the activation energy for a reaction by 10 kJ mol–1 at 300 K. 
The ratio of rate constants,
\(\frac{Κ′ , Catalysed}{Κ,Uncatalysed}\)
is ex. The value of x is ____.[nearest integer]
[Assume that the pre-exponential factor is same in both the cases Given R = 8.31 J K–1 mol–1]

When a gas filled in a closed vessel is heated by raising the temperature by 1ºC, its pressure increases by 0.4%. The initial temperature of the gas is _____ K.
identical drops are charged at 22 V each. They combine to form a bigger drop. The potential of the bigger drop will be ______ V.
The length of a given cylindrical wire is increased to double of its original length. The percentage increase in the resistance of the wire will be ______%.

In a series LCR circuit, the inductance, capacitance and resistance are L = 100 mH, C = 100 μF and R = 10 Ω respectively. They are connected to an AC source of voltage 220 V and frequency of 50 Hz. The approximate value of current in the circuit will be ______ A.

AC source of voltage 220 V and frequency of 50 Hz

Reaction of [Co(H2O)6]2+ with excess ammonia and in the presence of oxygen results into a diamagnetic product. Number of electrons present in t2g-orbitals of the product is _______

In an experiment of CE configuration of n–p–n transistor, the transfer characteristics are observed as given in figure. 

In an experiment of CE configuration of n–p–n transistor

If the input resistance is 200 Ω and output resistance is 60 Ω, the voltage gain in this experiment will be______.

The moles of methane required to produce 81 g of water after complete combustion is _____ × 10–2 mol. [nearest integer]
Let f: ℝ → ℝ satisfy f(x + y) = 2x f(y) + 4y f(x), ∀ x, y∈ ℝ. If f(2) = 3, then 14. f'(4)/f'(2) is equal to ___.