List of top Questions asked in JEE Main

For the following Assertion and Reason, the correct option is
Assertion : For hydrogenation reactions, the catalytic activity increases from Group 5 to Group 11 metals with maximum activity shown by Group 7-9 elements.
Reason : The reactants are most strongly adsorbed on group 7-9 elements.

The increasing order of the atomic radii of the following elements is :-
(a) C (b) O
(c) F (d) Cl
(e) Br

For the following Assertion and Reason, the correct option is :
Assertion : The pH of water increases with increase in temperature.
Reason : The dissociation of water into \(\mathrm{H^+}\) and \(\mathrm{OH^-}\) is an exothermic reaction.

The correct order of the calculated spin-only magnetic moments of complexs (A) to (D) is:
(A) \(\mathrm{Ni(CO)_4}\)
(B) \(\mathrm{[Ni(H_2O)_6]Cl_2}\)
(C) \(\mathrm{Na_2[Ni(CN)_4]}\)
(D) \(\mathrm{PdCl_2(PPh_3)_2}\)

Arrange the following bonds according to their average bond energies in descending order :
\(\mathrm{C{-}Cl},\ \mathrm{C{-}Br},\ \mathrm{C{-}F},\ \mathrm{C{-}I}\)

Three containers \(C_1\), \(C_2\) and \(C_3\) have water at different temperatures. The table below shows the final temperature \(T\) when different amounts of water (given in litres) are taken from each containers and mixed (assume no loss of heat during the process)

\(C_1\)	\(C_2\)	\(C_3\)	\(T\)
1 l	2 l	-	\(60^\circ\)C
-	1 l	2 l	\(30^\circ\)C
2 l	-	1 l	\(60^\circ\)C
1 l	1 l	1 l	\(\theta\)

The value of \(\theta\) (in \(^\circ\)C to the nearest integer) is ..........

An asteroid is moving directly towards the centre of the earth. When at a distance of \(10R\) (\(R\) is the radius of the earth) from the earths centre, it has a speed of \(12\ \mathrm{km/s}\). Neglecting the effect of earths atmosphere, what will be the speed of the asteroid when it hits the surface of the earth (escape velocity from the earth is \(11.2\ \mathrm{km/s}\)) ? Give your answer to the nearest integer in kilometer/s _____.

The first member of the Balmer series of hydrogen atom has a wavelength of 6561 \(\mathrm{\AA}\). The wavelength of the second member of the Balmer series (in nm) is:

A ball is dropped from the top of a 100 m high tower on a planet. In the last \(\frac{1}{2}\) s before hitting the ground, it covers a distance of 19 m. Acceleration due to gravity (in \(\mathrm{ms^{-2}}\)) near the surface on that planet is _____.

A carnot engine having an efficiency of \(\frac{1}{10}\) is being used as a refrigerator. If the work done on the refrigerator is 10 J, the amount of heat absorbed from the reservoir at lower temperature is :

A simple pendulum is being used to determine the value of gravitational acceleration \(g\) at a certain place. The length of the pendulum is 25.0 cm and a stop watch with 1 s resolution measures the time taken for 40 oscillations to be 50 s. The accuracy in \(g\) is :

The series combination of two batteries, both of the same emf 10 V, but different internal resistance of \(20\ \Omega\) and \(5\ \Omega\), is connected to the parallel combination of two resistors \(30\ \Omega\) and \(R\ \Omega\). The voltage difference across the battery of internal resistance \(20\ \Omega\) is zero, the value of \(R\) (in \(\Omega\)) is : _______

A uniform sphere of mass 500 g rolls without slipping on a plane horizontal surface with its centre moving at a speed of 5.00 cm/s. Its kinetic energy is :

A particle of mass \(m\) is dropped from a height \(h\) above the ground. At the same time another particle of the same mass is thrown vertically upwards from the ground with a speed of \(\sqrt{2gh}\). If they collide head-on completely inelastically, the time taken for the combined mass to reach the ground, in units of \(\sqrt{\frac{h}{g}}\) is :

A plane electromagnetic wave of frequency 25 GHz is propagating in vacuum along the z-direction. At a particular point in space and time, the magnetic field is given by \(\vec{B} = 5 \times 10^{-8}\,\hat{j}\,\mathrm{T}\). The corresponding electric field \(\vec{E}\) is (speed of light \(c = 3 \times 10^8\) ms^-1)

Consider two charged metallic spheres \(S_1\) and \(S_2\) of radii \(R_1\) and \(R_2\), respectively. The electric fields \(E_1\) (on \(S_1\)) and \(E_2\) (on \(S_2\)) on their surfaces are such that \(E_1/E_2 = R_1/R_2\). Then the ratio \(V_1\) (on \(S_1\)) / \(V_2\) (on \(S_2\)) of the electrostatic potentials on each sphere is :

A galvanometer having a coil resistance \(100\ \Omega\) gives a full scale deflection when a current of 1 mA is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter giving full scale deflection for a potential difference of 10 V?

A transverse wave travels on a taut steel wire with a velocity of \(v\) when tension in it is \(2.06 \times 10^4\) N. When the tension is changed to \(T\), the velocity changed to \(v/2\). The value of \(T\) is close to :

The sum, \(\sum_{n=1}^{7} \frac{n(n+1)(2n+1)}{4}\) is equal to ________.

If \(\frac{\sqrt{2}\sin\alpha}{\sqrt{1 + \cos 2\alpha}} = \frac{1}{7}\) and \(\sqrt{\frac{1 - \cos 2\beta}{2}} = \frac{1}{\sqrt{10}}\), \(\alpha, \beta \in \left(0, \frac{\pi}{2}\right)\), then \(\tan(\alpha + 2\beta)\) is equal to _____.

The number of 4 letter words (with or without meaning) that can be formed from the eleven letters of the word 'EXAMINATION' is _______.

Let a line \(y = mx\) \((m \gt 0)\) intersect the parabola, \(y^2 = x\) at a point P, other than the origin. Let the tangent to it at P meet the x-axis at the point Q. If area \((\Delta OPQ) = 4\) sq. units, then m is equal to __________.

If a line, \(y = mx + c\) is a tangent to the circle, \((x - 3)^2 + y^2 = 1\) and it is perpendicular to a line \(L_1\), where \(L_1\) is the tangent to the circle, \(x^2 + y^2 = 1\) at the point \(\left(\frac{1}{\sqrt{2}}, \frac{1}{\sqrt{2}}\right)\), then :

The differential equation of the family of curves, \(x^2=4b(y+b)\), \(b\in\mathbb{R}\), is :

The length of the perpendicular from the origin, on the normal to the curve, \(x^2+2xy-3y^2=0\) at the point \((2,2)\) is