List of top Questions asked in JEE Main

In Goldschmidt aluminothermic process which of the following reducing agents is used:

The rate constant of a zero order reaction is $2.0 \times 10^{-2}\, mol \,L^{-1}\, s^{-1}$. If the concentration of the reactant after $25$ seconds is $0.5\,M$. What is the initial concentration ?

Copper crystallises in fcc with a unit length of $361\,pm$. What is the radius of copper atom ?

In which of the following pairs of molecules/ions both the species are not likely to exist?

In a face centred cubic lattice, atoms of $A$ form the comer points and atoms of $B$ form the face centred points. If two atoms of $A$ are missing from the comer points, the formula of the ionic compound is :

The first ionisation potential of $Na$ is $5.1\, eV$. The value of electron gain enthalpy of $Na^+$ will be

Electron gain enthalpy with negative sign of fluorine is less than that of chlorine due to :

The surface charge density of a thin charged disc of radius $R$ is $\sigma$. The value of the electric field at the centre of the disc is $\frac{\sigma}{2 \in_{0}} \cdot$ With respect to the field at the centre, the electric field along the axis at a distance $R$ from the centre of the disc :

Which of the following is the wrong statement?

Vapour pressure of pure benzene is $119$ torr and that of toluene is $37.0$ torr at the same temperature. Mole fraction of toluene in vapour phase which is in equilibrium with a solution of benzene and toluene having a mole fraction of toluene $0.50$, will be :

Which has trigonal bipyramidal shape ?

Let $x_1 , x_2,...., x_n$ be n observations, and let $\bar{x}$ be their arithmetic mean and $\sigma^2$ be the variance. Variance of $2x_1, 2x_2, ..., 2x_n$ is $4 \sigma^2$. Arithmetic mean $2x_1, 2x_2, ..., 2x_n $ is 4 $\bar{x}$ .

Let R be the set of real numbers A = {(x, y) $\in$ R $\times$ R : y - x is an integer} is an equivalence relation on R. B = {(x, y) $\in$ R $\times$ R : x = $\alpha$y for some rational number $\alpha$} is an equivalence relation on R.

If $ {{\cos }^{-1}}\left( \frac{5}{13} \right)-{{\sin }^{-1}}\left( \frac{12}{13} \right)={{\cos }^{-1}}x, $ then $ x $ is equal to

The variance of first n even natural numbers is $\frac{n^2 - 1}{4}$. The sum of first n natural numbers is $\frac{n(n + 1)}{2}$ and the sum of squares of first n natural numbers is $\frac{n(n + 1)(2n +1)}{6}$.

Which of the following statements is true?

An artificial radioactive isotope gave ${^{14}_{7}N}$ after two successive $\beta$ -particle emissions. The number of neutrons in the parent nucleus must be :

The vector sum of two forces is perpendicular to their vector differences. In that case the forces

Probability of four sons to a couple is

The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiation

Match List I with List II:

List I		List II
A	Intrinsic Semiconductor	I	Fermi-level near the conduction band
B	n-type semiconductor	II	Fermi-level in the middle of valence and conduction band
C	p-type semiconductor	III	Fermi-level near the valence band
D	Metals	IV	Fermi-level inside the conduction band

Choose the correct answer from the options given below:

The resistance \( R = \frac{V}{I} \) where \( V = (200 \pm 5) \, \text{V} \) and \( I = (20 \pm 0.2) \, \text{A} \). The percentage error in the measurement of \( R \) is:

If solution of differential equation xdy - ydx = xy(xdy - ydx) and y(1) = 1 is α|y| = |x|e^{(xy - β)} then (α + β) is equal to

An equilateral triangle ABC formed from a uniform wire has two small identical beads initially located at A. The triangle is set rotating about the vertical axis AO. Then the beads are released from rest simultaneously and allowed to slide down, one along AB and other along AC as shown. Neglecting frictional effects, the quantities that are conserved as the beads slide down are:

Angular momentum of an electron in an orbit of radius R of a hydrogen atom is directly proportional to