List of top Questions asked in JEE Main

Match List - I with List - II :
List - I (a) Mercury (b) Copper (c) Silicon (d) Nickel
List - II (i) Vapour phase refining (ii) Distillation Refining (iii) Electrolytic Refining (iv) Zone Refining Choose the most appropriate answer from the option given below :
In basic medium, H₂O₂ exhibits which of the following reactions ? (A) Mn²⁺ → Mn⁴⁺ (B) I₂ → I⁻ (C) PbS → PbSO₄ Choose the most appropriate answer from the options given below :
Match List - I with List - II : List - I (a) Be (b) Mg (c) Ca (d) Ra List - II (i) treatment of cancer (ii) extraction of metals (iii) incendiary bombs and signals (iv) windows of X-ray tubes (v) bearings for motor engines. Choose the most appropriate answer from the option given below :
A TV transmission tower antenna is at a height of 20 m. Suppose that the receiving antenna is at. (i) ground level (ii) a height of 5 m. The increase in antenna range in case (ii) relative to case (i) is n%. The value of n, to the nearest integer, is __________.
The radius of a sphere is measured to be (7.50 ± 0.85) cm. Suppose the percentage error in its volume is x. The value of x, to the nearest integer, is __________.
Which of the following statements are correct?
(A) Electric monopoles do not exist whereas magnetic monopoles exist.
(B) Magnetic field lines due to a solenoid at its ends and outside cannot be completely straight and confined.
(C) Magnetic field lines are completely confined within a toroid.
(D) Magnetic field lines inside a bar magnet are not parallel.
(E) χ = -1 is the condition for a perfect diamagnetic material, where χ is its magnetic susceptibility.
Choose the correct answer from the options given below:
Consider a uniform wire of mass \(M\) and length \(L\). It is bent into a semicircle. Its moment of inertia about a line perpendicular to the plane of the wire passing through the centre is:
The speed of electrons in a scanning electron microscope is \(1 \times 10^7\) ms⁻¹. If the protons having the same speed are used instead of electrons, then the resolving power of scanning proton microscope will be changed by a factor of:
Consider a sample of oxygen behaving like an ideal gas. At 300 K, the ratio of root mean square (rms) velocity to the average velocity of gas molecule would be: (Molecular weight of oxygen is 32 g/mol; R = 8.3 J K⁻¹ mol⁻¹)
An object of mass \(m_1\) collides with another object of mass \(m_2\), which is at rest. After the collision the objects move with equal speeds in opposite direction. The ratio of the masses \(m_2 : m_1\) is:
Let \( P = \begin{bmatrix} 3 & -1 & -2 \\ 2 & 0 & \alpha \\ 3 & -5 & 0 \end{bmatrix} \), where \( \alpha \in \mathbb{R} \). Suppose \( Q = [q_{ij}] \) is a matrix satisfying \( PQ = k I_3 \) for some non-zero \( k \in \mathbb{R} \). If \( q_{23} = -\dfrac{k}{8} \) and \( |Q| = \dfrac{k^3}{2} \), then \( \alpha^2 + k^2 \) is equal to __________.
The equation of the plane passing through the point (1, 2, -3) and perpendicular to the planes $3x + y - 2z = 5$ and $2x - 5y - z = 7$, is :
The system of linear equations 3x - 2y - kz = 10, 2x - 4y - 2z = 6, x + 2y - z = 5m is inconsistent if :
If \( f(x) = [x - 1]\cos\!\left( \frac{2x - 1}{2}\pi \right) \), then \( f \) is :
The function \( f(x) = \dfrac{4x^3 - 3x^2}{6} - 2 \sin x + (2x - 1)\cos x \) :
\( \displaystyle \lim_{x \to 0} \frac{\int_{0}^{x^2} \sin(\sqrt{t}) \, dt}{x^3} \) is equal to :
Let \( p \) and \( q \) be two positive numbers such that \( p + q = 2 \) and \( p^4 + q^4 = 272 \). Then \( p \) and \( q \) are roots of the equation :

Identify products A and B. $CH_3 - CH(CH_3) - CH_3 \xrightarrow{\text{dil. } KMnO_4, 273 K} A \xrightarrow{CrO_3} B$ 

The product formed in the first step of the reaction of $CH_3 - CH_2 - CH(Br) - CH_2 - CH(Br) - CH_3$ with excess $Mg/Et_2O$ is :

What is the major product formed by HI reaction with

The electrode potential of \( \mathrm{M^{2+}/M} \) of 3d-series elements shows positive value for :
\( \mathrm{Al_2O_3} \) was leached with alkali to get \( X \). The solution of \( X \), on passing the gas \( Y \), forms \( Z \). \( X, Y \) and \( Z \) respectively are :

In Freundlich adsorption isotherm, slope of AB line is : 

In the given figure, energy levels of H-atom are shown. Transitions A ($n=\infty \to 1$), B ($n=4 \to 2$), C ($n=4 \to 3$) represent : 

If the velocity-time graph has the shape AMB (where M is a peak), what would be the shape of the corresponding acceleration-time graph ?