List of top Chemistry Questions asked in JEE Main

The predominant form of histamine present in human blood is $(pK_a$ Histidine $= 6.0)$

The ratio of mass percent of $C$ and $H$ of an organic compound $\left( C _{ X } H _{ Y } O _{ Z }\right)$ is $6: 1 .$ If one molecule of the above compound $\left( C _{ X } H _{ Y } O _{ Z }\right)$ contains half as much oxygen as required to burn one molecule of compound $C _{X} H_{Y}$ completely to $CO _{2}$ and $H _{2} O$. The empirical formula of compound $C _{ X } H _{ Y } O _{ Z }$ is

Two moles of an ideal monoatomic gas occupies a volume $V$ at $27^{\circ}C$. The gas expands adiabatically to a volume $2V$. Calculate $(a)$ the final temperature of the gas and $(b) $ change in its internal energy -

$N_2O_5$ decomposes to $NO_2$ and $O_2$ and follows first order kinetics. After $50$ minutes, the pressure inside the vessel increases from $50\, mm\, Hg$ to $87.5\, mm\, Hg.$ The pressure of the gaseous mixture after $100$ minute at constant temperature will be :

Phenol reacts with methyl chloroformate in the presence of $NaOH$ to form product $A, A$ reacts with $Br_2$ to form product $B. A$ and $B$ are respectively :

The trans-alkenes are formed by the reduction of alkynes with :

A water sample has ppm level concentration of following anions $F^{-} = 10 ;\, SO^{2-}_4 = 100 ;\, NO^{-}_3 = 50$ The anion/anions that make/makes the water sample unsuitable for drinking is / are :

$\Delta U $ is equal to :

An ideal gas undergoes isothermal expansion at constant pressure. During the process :

Among the following, the incorrect statement is :

For a reaction, $ {A_(g) \to A_(l); \Delta H = - 3RT}$. The correct statement for the reaction is :

$3$-Methylpent-$2$-ene on reaction with $HBr$ in presence of peroxide forms an addition product. The number of possible stereoisomers for the product is :

1 gram of a carbonate $(M_2CO_3)$ on treatment with excess $HCl$ produces $0.01186$ mole of $CO_2$. The molar mass of $M_2CO_3$ in g $mol^{-1}$ is :

Among the following, correct statement is :

Excess of $NaOH_{(aq)}$ was added to $100\, mL$ of ${ FeCl_3}$ (aq) resulting into $2.14\, g$ of ${Fe(OH)_3}$. The molarity of ${FeCl_3}$ (aq) is : (Given molar mass of ${Fe = 56 \, g \, mol^{-1}}$ and molar mass of ${Cl = 35.5 \, g \, mol^{-1}}$)

What is the standard reduction potential $(E^{\circ}) $ for ${Fe^{3+} \to Fe}$ ? Given that : ${Fe^{2+} + 2e^{-} -> Fe ; E^{\circ}_{Fe^{2+} / Fe} = - 0.47 V }$ ${Fe^{3+} + e^{-} -> Fe^{2+} ; E^{\circ}_{Fe^{3+} / Fe^{2+}} = + 0.77 V }$

If the shortest wavelength in Lyman series of hydrogen atom is $A$, then the longest wavelength in Paschen series of $He^{+}$ is :

Which of the following ions does not liberate hydrogen gas on reaction with dilute acids?

The group having triangular planar structures is :

The electronic configuration with the highest ionization enthalpy is :

The electron in the hydrogen atom undergoes transition from higher orbitals to orbital of radius $211.6\, pm$. This transition is associated with

A metal crystallises in a face centred cubic structure. If the edge length of its unit cell is $'a'$, the closest approach between two atoms in metallic crystal will be :

Addition of sodium hydroxide solution to a weak acid (HA) results in a buffer of pH 6. If ionisation constant of HA is $10^{-5}$, the ratio of salt to acid concentration in the buffer solution will be :

Among the following, the essential amino acid is :