List of top Questions asked in JEE Main

Let $\eta_1$ is the efficiency of an engine at $T _1=447^{\circ} C$ and $T _2=147^{\circ} C$ while $\eta_2$ is the efficiency at $T _1=947^{\circ} C$ and $T _2=47^{\circ} C$ The ratio $\frac{\eta_1}{\eta_2}$ will be :

If half life for a radioactive decay reaction is T. Find the time after which $\frac{7}{8}th$ of initial mass decays

For a particle performing linear SHM, its position (x) as a function of time (t) is given by x = Asin(ωt + δ). Given that, at t = 0, particle is at +A/2 and is moving towards x = +A. Find δ

Given below are two statements:
Statement I : The diamagnetic property depends on temperature.
Statement II : The included magnetic dipole moment in a diamagnetic sample is always opposite to the magnetizing field.
In the light of given statement, choose the correct answer from the options given below:

The distance travelled by a particle is related to time $t$ as $x=4 t^2$ The velocity of the particle at $t-5 s$ is:-

Electron beam used in an electron microscope, when accelerated by a voltage of $20 kV$, has a de-Broglie wavelength of $\lambda_0$. If the voltage is increased to $40 kV$, then the de-Broglie wavelength associated with the electron beam would be:

Ratio between rms speed of Ar to the most probable speed of $O^2$ at $27\degree C$ is

Let A=$\begin{bmatrix} 1 & \frac{1}{51} \\ 0 & 1\end{bmatrix}$. If B=$\begin{bmatrix} 1 & 2 \\ -1 & -1\end{bmatrix}$A $\begin{bmatrix} -1 & -2 \\ 1 & 1\end{bmatrix}$, then the sum of all the elements of the matrix $\sum^{50}_{n=1}B^n$ is equal to

Choose the correct option.

Consider the above reaction and identify the product B.

Assuming the earth to be a sphere of uniform mass density, the weight of a body at a depth $d=\frac{R}{2}$ from the surface of earth, if its weight on the surface of earth is 200 N, will be

Find the equivalent resistance across A and B for given circuit.

A radioactive nuclei X decays simultaneously to two nuclei Y and Z as:

t_½ is 12 minutes while t'_½ is 3 minutes. Find the time in which nuclei X decays 50%.

$tan^{-1}(\frac {1+\sqrt 3}{3+\sqrt 3})+sec^{-1}(\sqrt {\frac {8+4\sqrt 3}{3+3\sqrt 3})}$ is equal to:

'X' is:

Pick the correct graph between potential V at distance r from centre for the uniformly charged spherical shell of radius R.

α-particle, proton & electron have same kinetic energy. Select correct order of their de-Broglie wavelength.

Match List I with List I:

List I		List II
A	AM Broadcast	I	88-108 MHz
B	FM Broadcast	II	540-1600 kHz
C	Television	III	3.7-4.2 GHz
D	Satellite Communication	IV	54 MHz-890 MHz

Choose the correct answer from the options given below:

The correct sequence of reagents for the preparation of Q and R is:

Mass of body = 500 kg, μ= 0.7. Find work required to move a distance of 4 Km if the body moves with velocity 10 m/s.

Statement (1): A truck and a car moving with equal kinetic energy are stopped by equal retarding force. Both will cover equal distance to stop.
Statement (2): A car moving towards east suddenly changes its direction towards north with same speed. Its acceleration is zero.
In the light of given statements, choose the most appropriate answer from the options given below.

Match the physical quantity in column-I with the respective dimension in column-II and choose the correct option.

	Column-I		Column-II
I.	Spring constant	(P)	[ML²T⁰ ]
II.	Moment of inertia	(Q)	[M⁰L⁰T^–1 ]
III.	Angular momentum	(R)	[ML⁰T^–2 ]
IV.	Angular speed	(S)	[ML²T^–1 ]

The length of a conductor having resistance 160 Ω, is compressed to 25% of its initial value. The new resistance will be

Statement I : In LCR circuit, by increasing frequency current increases first then decreases.
Statement II : Power factor of LCR circuit is one.
Choose the correct option.

Assertion (A): An electrical dipole is enclosed in a closed gaussian surface. The total flux through the enclosed surface is zero.
Reason (R): Net charge inside the enclosed surface is zero.