List of top Questions asked in JEE Main- 2021

Spin only magnetic moment of an octahedral complex of \(\mathrm{Fe^{2+}}\) in the presence of a strong field ligand in BM is :

Outermost electronic configuration of a group 13 element, E, is \(4s^2, 4p^1\). The electronic configuration of an element of p-block period-five placed diagonally to element, E is :

A body rotating with an angular speed of 600 rpm is uniformly accelerated to 1800 rpm in 10 sec. The number of rotations made in the process is ___________.

Which one of the following pairs of isomers is an example of metamerism?

A series LCR circuit of R = 5 \(\Omega\), L = 20 mH and C = 0.5 \(\mu\)F is connected across an AC supply of 250 V, having variable frequency. The power dissipated at resonance condition is ______________ \(\times\) \(10^{2}\) W.

One mole of an ideal gas at \(27^\circ\) is taken from A to B as shown in the given PV indicator diagram. The work done by the system will be _________ \(\times\) \(10^{-1}\) J. [Given : R = 8.3 J/mole K, ln2 = 0.6931] (Round off to the nearest integer)

A radioactive substance decays to \(\left(\frac{1}{16}\right)^{th}\) of its initial activity in 80 days. The half life of the radioactive substance expressed in days is ____________.

Two bodies, a ring and a solid cylinder of same material are rolling down without slipping an inclined plane. The radii of the bodies are same. The ratio of velocity of the centre of mass at the bottom of the inclined plane of the ring to that of the cylinder is \(\frac{\sqrt{x}}{2}\). Then, the value of x is _____________.

For a certain radioactive process the graph between ln R and t(sec) is obtained as shown in the figure. Then the value of half life for the unknown radioactive material is approximately :

In the given figure switches \(S_1\) and \(S_2\) are in open condition. The resistance across ab when the switches \(S_1\) and \(S_2\) are closed is _____________ \(\Omega\).

A zener diode having zener voltage 8 V and power dissipation rating of 0.5 W is connected across a potential divider arranged with maximum potential drop across zener diode is as shown in the diagram. The value of protective resistance \(R_p\) is .................... \(\Omega\).

A body of mass 'm' is launched up on a rough inclined plane making an angle of 30\(^\circ\) with the horizontal. The coefficient of friction between the body and plane is \(\dfrac{\sqrt{x}}{5}\) if the time of ascent is half of the time of descent. The value of x is __________.

At an angle of 30\(^\circ\) to the magnetic meridian, the apparent dip is 45\(^\circ\). Find the true dip :

Consider a binary star system of star A and star B with masses \(m_A\) and \(m_B\) revolving in a circular orbit of radii \(r_A\) an \(r_B\), respectively. If \(T_A\) and \(T_B\) are the time period of star A and star B, respectively,

Then :

A body at rest is moved along a horizontal straight line by a machine delivering a constant power. The distance moved by the body in time 't' is proportional to :

Two small drops of mercury each of radius R coalesce to form a single large drop. The ratio of total surface energy before and after the change is :

A body rolls down an inclined plane without slipping. The kinetic energy of rotation is 50% of its translational kinetic energy. The body is :

The correct relation between the degrees of freedom f and the ratio of specific heat \(\gamma\) is :

A particle is making simple harmonic motion along the X-axis. If at a distances \(x_1\) and \(x_2\) from the mean position the velocities of the particle are \(v_1\) and \(v_2\) respectively. The time period of its oscillation is given as :

If time (t), velocity (v), and angular momentum (l) are taken as the fundamental units. Then the dimension of mass (m) in terms of t, v and l is :

An electron having de-Broglie wavelength \(\lambda\) is incident on a target in a X-ray tube. Cut-off wavelength of emitted X-ray is :

In an electromagnetic wave the electric field vector and magnetic field vector are given as \(\vec{E} = E_0\hat{i}\) and \(\vec{B} = B_0\hat{k}\) respectively. The direction of propagation of electromagnetic wave is along :

With what speed should a galaxy move outward with respect to earth so that the sodium-D line at wavelength 5890 \(\mathring{A}\) is observed at 5896 \(\mathring{A}\) ?

Which of the following graphs represent the behavior of an ideal gas? Symbols have their usual meaning.

For a series LCR circuit with R = 100 \(\Omega\), L = 0.5 mH and C = 0.1 pF connected across 220V\(-\)50 Hz AC supply, the phase angle between current and supplied voltage and the nature of the circuit is :