List of top Questions asked in JEE Main

Monocarboxylic acids are functional isomers of:

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

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

Correct set up to verify Ohm?s law is :

A charge Q is uniformly distributed over a long rod AB of length L as shown in the figure. The electric potential at the point O lying at distance L from the end A is

A vessel contains a mixture of $1$ mole of oxygen and two moles of nitrogen at $300 \,K$. The ratio of the rotational kinetic energy per $ O_{2} $ molecule to that per $ N_{2} $ molecule is

Which of the free radical is most stable?

If $ X+Y=\left[ \begin{matrix} 7 & 0 \\ 2 & 5 \\ \end{matrix} \right] $ and $ X-Y=\left[ \begin{matrix} 3 & 0 \\ 0 & 3 \\ \end{matrix} \right] $ , then X is equal to

The density of $3M$ solution of sodium chloride is $1.252\, g\, mL^{-1}$. The molality of the solution will be: (molar mass, $NaCl = 585\, g\, mol^{-1}$)

Number of atoms in the following samples of substances is largest in :

$10\, mL$ of $2(M)$ $NaOH$ solution is added to $200\, mL$ of $0.5 (M)$ of $NaOH$ solution. What is the final concentration ?

$6$ litres of an alkene require $27$ litres of oxygen at constant temperature and pressure for complete combustion. The alkene is:

If the equations $x^2+2x+3=0$ and $ax^2+bx+c=0, a, b, c \in R$ have a common root, then $a : b : c$ is

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 :

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

\({(1) \,N_2(g) +3H_2(g)<=> 2NH_3(g), K_1}\)
\({(2) \,N_2(g) +O_2(g)<=> 2NHO(g), K_2}\) 
\({(3) \,H_2(g) +\frac{1}{2}O_2(g)<=> H_2O(g), K_3}\) 
The equation for the equilibrium constant of the reaction 
\({2NH_3(g) +\frac{5}{2}O_2(g)<=> 2NO(g), 3H_2O(g)}\), \((K_4)\) in terms of \(K_1\) and \(K_3\) is:

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

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

Which of the following represents the correct order of increasing first ionisation enthalpy for $Ca, Ba, S, Se$ and $Ar$?

For gaseous state, if most probable speed is denoted by $c *$, average speed by $\overline{C}$ and root square speed by $c$, then for a large number of molecules, the ratios of these speeds are

Given, $E^\circ _{Cr ^{3+}/Cr} =-0.74\, V;E^\circ_{MnO^-_4/Mn^{2+}}=1.51\, V$ $\, \, \, \, \, E^\circ _{Cr_2 O ^{2-}_7/Cr^{3+}} =-1.33\, V;E^\circ_{Cl/Cl^-}=1.36\, V$ Based on the data given above strongest oxidising agent will be

Which one of the following molecules is expected to exhibit diamagnetic behaviour?

The rate of a reaction doubles when its temperature changes from $300\, K$ to $310\,K$. Activation energy of such a reaction will be $(R = 8.314 JK^{-1} \,mol^{-1}$ and $log \,2 = 0.301)$

Four successive members of the first row transition elements listed below with atomic numbers. Which one of them is expected to have the highest $E_{m{^{3+}}/m{^{2+}}}^{\circ}$value?

Consider the following reaction, $xMnO_4^- + yC_2O_4^{2-}+zH^+ \rightarrow xMn^{2+}+2yCO_2 + \frac{z}{2}H_2O$ The values of x, y and z in the reaction are, respectively