List of top Chemistry Questions asked in JEE Main

The common positive oxidation states for an element with atomic number 24, are :
The set that represents the pair of neutral oxides of nitrogen is :
The set of elements that differ in mutual relationship from those of the other sets is :
For the coagulation of a negative sol, the species below, that has the highest flocculating power is :
Fructose is an example of :
Match List - I with List - II :

List - IList - II
(a)\([\mathrm{Co(NH_3)_6}][\mathrm{Cr(CN)_6}]\)(i)Linkage isomerism
(b)\([\mathrm{Co(NH_3)_3(NO_2)_3}]\)(ii)Solvate isomerism
(c)\([\mathrm{Cr(H_2O)_6}]\mathrm{Cl_3}\)(iii)Co-ordination isomerism
(d)\(cis-[\mathrm{CrCl_2(ox)_2}]^{3-}\)(iv)Optical isomerism

Choose the correct answer from the options given below :
The correct pair(s) of the ambident nucleophiles is(are)
(A) \(\mathrm{AgCN/KCN}\)
(B) \(\mathrm{RCOOAg/RCOOK}\)
(C) \(\mathrm{AgNO_2/KNO_2}\)
(D) \(\mathrm{AgI/KI}\)
During which of the following processes, does entropy decrease?
(A) Freezing of water to ice at \(0^\circ\mathrm{C}\)
(B) Freezing of water to ice at \(-10^\circ\mathrm{C}\)
(C) \(\mathrm{N_2(g)+3H_2(g)\to2NH_3(g)}\)
(D) Adsorption of CO(g) on lead surface.
(E) Dissolution of NaCl in water
Choose the correct answer from the options given below :

In the above reaction, the structural formula of (A), "X" and "Y" respectively are :
Primary, secondary and tertiary amines can be separated using:
Given below are two statements :
Statement I : 2-methylbutane on oxidation with \(\mathrm{KMnO_4}\) gives 2-methylbutan-2-ol.
Statement II : n-alkanes can be easily oxidised to corresponding alcohols with \(\mathrm{KMnO_4}\).
Choose the correct option :
Nitrogen can be estimated by Kjeldahl's method for which of the following compound?
Choose the correct statement regarding the formation of carbocations A and B given.
\(\mathrm{C_{12}H_{22}O_{11}+H_2O\ \xrightarrow{\text{Enzyme A}}\ \underset{\text{Glucose}}{C_6H_{12}O_6}+\underset{\text{Fructose}}{C_6H_{12}O_6}}\)
\(\mathrm{\underset{\text{Glucose}}{C_6H_{12}O_6}\ \xrightarrow{\text{Enzyme B}}\ 2C_2H_5OH+2CO_2}\)
In the above reactions, the enzyme A and enzyme B respectively are :
Amongst the following, the linear species is :
The pressure exerted by a non-reactive gaseous mixture of 6.4g of methane and 8.8 g of carbon dioxide in a 10L vessel at 27\(^\circ\)C is __________ kPa. (Round off to the Nearest Integer).

[Assume gases are ideal, R = 8.314 J \(\mathrm{mol^{-1}\ K^{-1}}\)

Atomic masses : C : 12.0 u, H : 1.0 u, O : 16.0 u]
The mole fraction of a solute in a 100 molal aqueous solution is ___________ \(\times\) \(10^{-2}\). (Round off to the Nearest Integer).

[Given : Atomic masses : H : 1.0 u, O : 16.0 u ]
The oxygen dissolved in water exerts a partial pressure of 20 kPa in the vapour above water. The molar solubility of oxygen in water is __________ \(\times\) \(10^{-5}\) \(\mathrm{mol\ dm^{-3}}\). (Round off to the Nearest Integer).

[Given : Henry's law constant = \(K_H\) = 8.0 \(\times\) \(10^4\) kPa for \(\mathrm{O_2}\). Density of water with dissolved oxygen = 1.0 kg \(\mathrm{dm^{-3}}\) ]
For a certain first order reaction 32% of the reactant is left after 570s. The rate constant of this reaction is _________ \(\times 10^{-3}\ \mathrm{s^{-1}}\). (Round off to the Nearest Integer). [Given : \(\log_{10}2 = 0.301\), \(\ln 10 = 2.303\)]
The standard enthalpies of formation of \(\mathrm{Al_2O_3}\) and \(\mathrm{CaO}\) are \(-1675\) kJ \(\mathrm{mol^{-1}}\) and \(-635\) kJ \(\mathrm{mol^{-1}}\) respectively.

For the reaction

\(\mathrm{3CaO + 2Al \to 3Ca + Al_2O_3}\) the standard reaction enthalpy \(\Delta_rH^0\) = _________ kJ.

(Round off to the Nearest Integer)
The reaction of white phosphorus on boiling with alkali in inert atmosphere resulted in the formation of product 'A'. The reaction of 1 mol of 'A' with excess of \(\mathrm{AgNO_3}\) in aqueous medium gives ___________ mol(s) of Ag. (Round off to the Nearest Integer).

In the above reaction, 3.9 g of benzene on nitration gives 4.92 g of nitrobenzene. The percentage yield of nitrobenzene in the above reaction is ________\(\%\). (Round off to the Nearest Integer).

(Given atomic mass : C : 12.0 u, H : 1.0 u, O : 16.0 u, N : 14.0 u)
The correct order of conductivity of ions in water is :
The point of intersection and sudden increase in the slope, in the diagram given below, respectively, indicates :

Reducing smog is a mixture of :