List of top Questions asked in JEE Main

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)

 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)
\(lim(x→\frac{x}{2}) tan^2x((2sin^2x+3sinx+4)^{\frac{1}{2}}-(sin^2x+6sinx+2)^{\frac{1}{2}}\) is equal to.

Match List-I with List-II.

List-IList-II
(A) N2(g) + 3H2(g) → 2NH3(g)(I) Cu
(B) CO(g) + 3H2(g) → CH4(g) + H2O(g)(II) Cu/ZnO – Cr2O3
(C) CO(g) + H2(g) → HCHO(g)(III) FexOy + K2O + Al2O3
(D) CO(g) + 2H2(g) → CH3OH(g)(IV) Ni

Choose the correct answer from the options given below :

Melamine polymer is formed by the condensation of :

Among Co3+, Ti2+, V2+ and Cr2+ ions, one if used as a reagent cannot liberate H2 from dilute mineral acid solution, its spin-only magnetic moment in gaseous state is________ B.M. (Nearest integer)

Most stable product of the following reaction is :
Most stable product

The depression in the freezing point observed for a formic acid solution of concentration 0.5 mL L–1 is 0.0405°C. Density of formic acid is 1.05 g mL–1. The Van’t Hoff factor of the formic acid solution is nearly (Given for water kf = 1.86 k kg mol–1)

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 :

Among the following species
N2,N2+,N2−,N22−,O2,O2+,O2−,O22−
the number of species showing diamagnetism is ________.
A metre scale is balanced on a knife edge at its centre. When two coins, each of mass 10 g are put one on the top of the other at the 10.0 cm mark the scale is found to be balanced at the 40.0 cm mark. The mass of the metre scale is found to be \(x\times 10^{-2}\) kg. The value of x is _________.
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 half-life for the decomposition of gaseous compound A is 240 s when the gaseous pressure was 500 torr initially. When the pressure was 250 torr, the half-life was found to be 4.0 min. The order of the reaction is ______. (Nearest integer)

The geometry around boron in the product ‘B’ formed from the following reaction is

The enthalpy of combustion of propane, graphite and dihydrogen at 298 K are –2220.0 kJ mol–1, –393.5 kJ mol–1 and –285.8 kJ mol–1, respectively. The magnitude of enthalpy of formation of propane (C3H8) is _____ kJ mol–1. (Nearest integer)

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]

The compound(s) that is(are) removed as slag during the extraction of copper is
(A)CaO,(B)FeO,(C)Al2O3,(D)ZnO,(E)NiO
Choose the correct answer from the options given below :

\(\lim_{{x \to 0}} \limits\) \(\frac{cos(sin x)  -  cos x }{x^4}\) is equal to :

While estimating the nitrogen present in an organic compound by Kjeldahl’s method, the ammonia evolved from 0.25g of the compound neutralized 2.5mL of 2M H2SO4. The percentage of nitrogen present in organic compound is ________

Which one of the following reactions does not represent correct combination of substrateand product under the given conditions?

The number of N atoms in \(681\ g\) of \(C_7H_5N_3O_6\) is \(x × 10^{21}\). The value of \(x\) is ______ . (\(N_A\) = \(6.02 × 10^{23}\ mol^{–1}\)) (Nearest Integer)

The photochemical smog does not generally contain :

Which of the following sets of quantum numbers is not allowed?

If the area of the region \(\{(x, y) : x^{2/3} + y^{2/3} \leq 1, x + y \geq 0, y \geq 0\}\) is A, then \(\frac{(256 A)}{\pi} \)is equal to_______.

If y = y(x) is the solution of the differential equation

\(2x^2\frac{dy}{dx}-2xy+3y^2=0\) such that \(y(e)=\frac{e}{3},\)

then y(1) is equal to