List of top Questions asked in JEE Main

Select the correct statement from the following

Two blocks of mass $M_1 = 20\, kg$ and $M_2 = 12\, kg$ are connected by a metal rod of mass $8\, kg$. The system is pulled vertically up by applying a force of $480\, N$ as shown. The tension at the mid-point of the rod is :

A metallic rod of length $l$ is tied to a string of length $2l$ and made to rotate with angular speed ($\omega$ on a horizontal table with one end of the string fixed. If there is a vertical magnetic field $B$ in the region, the emf induced across the ends of the rod is

Two short bar magnets of length $1\, cm$ each have magnetic moments $1.20 \,Am^2 $ and $1.00 \,Am^2 $ respectively. They are placed on a horizontal table parallel to each other with their $N$ poles pointing towards the south. They have a common magnetic equator and are separated by a distance of $20.0\, cm$. The value of the resultant horizontal magnetic induction at the mid-point $O$ of the line joining their centres is close to (Horizontal component of the earth's magnetic induction is $ 3.6 \times {10}^{-5} W b/m^2$

Correct set up to verify Ohm?s law is :

In a metre bridge experiment null point is obtained at $40\, cm$ from one end of the wire when resistance $X$ is balanced against another resistance $Y$. If $X < Y$, then the new position of the null point from the same end, if one decides to balance a resistance of $3X$ against $Y$, will be close to:

Let $A (-3,2)$ and $B (-2,1)$ be the vertices of a triangle $ABC$. If the centroid of this triangle lies on the line $3x + 4y+2 = 0$, then the vertex $C$ lies on the line :

A tangent to the hyperbola $\frac{x^{4}}{4}-\frac{y^{2}}{2}=1$ meets x-axis at $P$ and y-axis at $Q$. Lines $PR$ and $QR$ are drawn such that $OPRQ$ is a rectangle (where $O$ is the origin). Then $R$ lies on :

Calcination is the process in which:

Electrode potentials (E$^{\circ}$) are given below : $Cu^{+}/Cu=+0.52\, V,$ $Fe^{3+}/Fe^{2+} = +0.77 \,V,$ $\frac{1}{2}I_{2}\left(s\right)/I^{-} = 40.54 \,V,$ $Ag^{+}/Ag =+ 0.88\,V.$ Based on the above potentials, strongest oxidizing agent will be :

Oxidation state of sulphur in anions $SO^{2-}_{3}. S_{2}O^{2-}_{4}$ and $S_{2}O^{2-}_{6}$ increases in the orders:

A light ray falls on a square glass slab as shown in the diagram. The index of refraction of the glass, if total internal reflection is to occur at the vertical face, is equal to :

An ideal gas at atmospheric pressure is adiabatically compressed so that its density becomes $32$ times of its initial value. If the final pressure of gas is $128$ atmospheres, the value of ?$\gamma$?of the gas is :

The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current $I$ of photocell varies as follows

A $12.5\, eV$ electron beam is used to bombard gaseous hydrogen at room temperature. It will emit :

The ellipse $E_1 : \frac{x^2}{9} + \frac{y^2}{4}$ = 1 is inscribed in a rectangle R whose sides are parallel to the coordinate axes. Another ellipse $E_2$ passing through the point (0, 4) circumscribes the rectangle R. The eccentricity of the ellipse $E_2$ is

Stability of the species $ Li_2 , Li_2^- , \, \, and \, \, Li_2^+ $ increases in the order of

For which of the following compounds Kjeldahl method can be used to determine the percentage of Nitrogen ?

A beam of unpolarized light of intensity $I_0$ is passed through a polaroid $A$ and then through another polaroid $B$ which is oriented so that its principal plane makes an angle of 45$^{\circ}$ relative to that of $A$. The intensity of the emergent light is

A diode detector is used to detect an amplitude modulated wave of $60\%$ modulation by using a condenser of capacity $250$ picofarad in parallel with a load resistance $100$ $\Omega$. Find the maximum modulated frequency which could be detected by it.

Experimentally it was found that a metal oxide has formula $ M_{0.98}O. $ Metal $M$, present as $ M^{2+} $ and $ M^{3+} $ in its oxide.Fraction of the metal which exists as $ M^{3+} $ would be

How many grams of methyl alcohol should be added to $10$ litre tank of water to prevent its freezing at $268\, K$ ? $\left(K_{f} \, for\, water\, is \,1.86 K\, kg \, mol^{-1} \right)$

A uniform wire (Young?s modulus $2 \times 10^{11}\,Nm^{-2}$) is subjected to longitudinal tensile stress of $5 \times 10^{7}\,Nm^{-2}$. If the overall volume change in the wire is $0.02\%$, the fractional decrease in the radius of the wire is close to:

To establish an instantaneous current of $2 A$ through a $1 \mu F$ capacitor; the potential difference across the capacitor plates should be changed at the rate of :