List of top Questions asked in JEE Main

$50\, mL$ of $0.5\, M$ oxalic acid is needed to neutralize $25\, mL$ of sodium hydroxide solution. The amount of $NaOH$ in $50\, mL$ of the given sodium hydroxide solution is :

For a reaction, $N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)$; identify dihydrogen $(H_2)$ as a limiting reagent in the following reaction mixtures.

Enthalpy of sublimation of iodine is $ {24 \; cal \; g^{-1}}$ at $200^{\circ}C$. If specific heat of $I_2(s)$ and $I_2(vap)$ are $0.055$ and $0.031\, cal\, g^{-1}K^{-1}$ respectively, then enthalpy of sublimation of iodine at $250^{\circ}C$ in $cal\, g^{-1}$ is :

For diatomic ideal gas in a closed system, which of the following plots does not correctly describe the relation between various thermodynamic quantities ?

For silver, $ {C_{p}(JK^{-1} mol^{-1}) = 23 + 0.01T}$. If the temperature (T) of $3$ moles of silver is raised from $300\,K$ to $1000\, K$ at $1\, atm$ pressure, the value of $\Delta H$ will be close to

$5$ moles of an ideal gas at $100\, K$ are allowed to undergo reversible compression till its temperature becomes $200\, K$. If $C_{V} =28 JK^{-1}mol^{-1} , caculate \Delta\, U$ and $\Delta \,pV $ for this process. ($R = 8.0 \, JK^{-1}mol^{-1}$]

Which one of the following statements regarding Henry's law not correct ?

For emission line of atomic hydrogen from $n_i = 8$ to $n_f $ = the plot of wave number $(\bar{v})$ against $( \frac{1}{n^2})$ will be (The Ry dberg constant, $R_H$ is in wave number unit).

Heat treatment of muscular pain involves radiation of wavelength of about $900\, nm$. Which spectral line of H-atom is suitable for this purpose ? $[R_H = 1 \times 10^5 \; cm^{-1}, h = 6.6 \times 10^{-34} \; Js, c = 3 \times 10^8 \; ms^{-1}]$

The size of the iso-electronic species $Cl^-, Ar$ and $ {Ca^{2+}}$ is affected by -

If surface tension (S), Moment of inertia (I) and Planck's constant (h), were to be taken as the fundamental units, the dimensional formula for linear momentum would be : -

A person standing on an open ground hears the sound of a jet aeroplane, coming from north at an angle $60^\circ$ with ground level. But he finds the aeroplane right vertically above his position. If $\upsilon$ is the speed of sound, speed of the plane is :

In a car race on straight road, car $A$ takes a time $t$ less than car $B$ at the finish and passes finishing point with a speed $'v'$ more than that of car $B$. Both the cars start from rest and travel with constant acceleration $a_1$ and $a_2$ respectively. Then $'v'$ is equal to :

In the cube of side $'a'$ shown in the figure, the vector from the central point of the face $ABOD$ to the central point of the face $BEFO$ will be:

Two vectors $\vec{A}$ and $\vec{B}$ have equal magnitudes. The magnitude of $(\vec{A} + \vec{B})$ is 'n' times the magnitude of $(\vec{A} - \vec{B})$ . The angle between $\vec{A}$ and $\vec{B}$ is :

In a hydrogen like atom, when an electron jumps from the $M$ - shell to the $L$ - shell, the wavelength of emitted radiation is $\lambda$. If an electron jumps from $N$-shell to the $L$-shell, the wavelength of emitted radiation will be :

A plano-convex lens (focal length $f_2$, refractive index $\mu_2$, radius of curvature $R$) fits exactly into a plano-concave lens (focal length $f_1$, refractive index $\mu_2$, radius of curvature R). Their plane surfaces are parallel to each other. Then, the focal length of the combination will be :

In an interference experiment the ratio of amplitudes of coherent waves is $\frac{a_1}{a_2} = \frac{1}{3}$ . The ratio of maximum and minimum intensities of fringes will be :

What is the position and nature of image formed by lens combination shown in figure? $(f_1, f_2$ are focal lengths)

One plano-convex and one plano-concave lens of same radius of curvature $'R'$ but of different materials are joined side by side as shown in the figure. If the refractive index of the material of $1$ is $\mu_1$ and that of $2$ is $\mu_2$, then the focal length of the combination is :

The eye can be regarded as a single refracting surface . The radius of curvature of this surface is equal to that of cornea ($7.8\, mm$ ). This surface separates two media of refractive indices 1 and $1.34$. Calculate the distance from the refracting surface at which a parallel beam of light will come to focus.

A wooden block floating in a bucket of water has $\frac{4}{5}$ of its volume submerged. When certain amount of an oil is poured into the bucket, it is found that the block is just under the oil surface with half of its volume under water and half in oil. The density of oil relative to that of water is :

A $15\, g$ mass of nitrogen gas is enclosed in a vessel at a temperature $27^{\circ}C$. Amount of heat transferred to the gas, so that rms velocity of molecules is doubled, is about : [Take R = 8.3 J/ K mole]

A vertical closed cylinder is separated into two parts by a frictionless piston of mass $m$ and of negligible thickness. The piston is free to move along the length of the cylinder. The length of the cylinder above the piston is $\ell_1$, and that below the piston is $\ell_2$ , such that $\ell_1$>$\ell_2$. Each part of the cylinder contains $n$ moles of an ideal gas at equal temperature $T$. If the piston is stationary, its mass, $m$, will be given by : (R is universal gas constant and $g$ is the acceleration due to gravity)

An ideal gas occupies a volume of $2\,m^3$ at a pressure of $3 \times 10^6\, Pa$. The energy of the gas is: