List of top Questions asked in JEE Main

Given below are two statements.
Statement-I: In CuSO4.5H2O, Cu-O bonds are present.
Statement-II: In CuSO4.5H2O, ligands coordinating with Cu(II) ion are O-and S-based ligands.
In the light of the above statements, choose the correct answer from the options given below:

Which of the following carbocations is most stable?
Match List-I with List-II
 List-I
(Complex)		 List-II
(Hybridization)
A.Ni(CO)4I.sp3
B.[Ni(CN)4]2-II.sp3d2
C.[Co(CN)6]3-III.d2sp3
D.[CoF6]3-IV.dsp2
Choose the correct answer from the options given below:
Statement-I : Leaching of gold with cyanide ion in absence of air/O2 leads to cyano complex of Au(III).
Statement-II : Zinc is oxidized during the displacement reaction carried out for gold extraction.
In the light of the above statements, choose the correct answer from the options given below.

In the metallurgical extraction of copper, following reaction is used :
FeO + SiO2 → FeSiO3 
FeO and FeSiO3 respectively are.

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Boric acid is a weak acid
Reason R: Boric acid is not able to release \(H^+\) ion on its own. It receives \(OH^–\) ion from water and releases \(H^+\) ion.
In the light of the above statements, choose the most appropriate answer from the options given below.
The measured BOD values for four different water samples (A-D) are as follows:
A = 3 ppm; B = 18 ppm; C = 21 ppm; D = 4 ppm;. The water samples which can be called as highly polluted with organic wastes, are
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R. 
Assertion A: Permanganate titrations are not performed in presence of hydrochloric acid. 
Reason R: Chlorine is formed as a consequence of oxidation of hydrochloric acid. 
In the light of the above statements, choose the correct answer from the options given below.
Which is true about Buna-N?
It has been found that for a chemical reaction with rise in temperature by 9 K the rate constant gets doubled. Assuming a reaction to be occurring at 300 K, the value of activation energy is found to be _________kJ mol–1. [nearest integer] (Given ln10 = 2.3, R = 8.3 J K–1 mol–1, log 2 = 0.30)
The complete combustion of 0.492 g of an organic compound containing ‘C’, ‘H’ and ‘O’ gives 0.793 g of CO2 and 0.442 g of H2O. The percentage of oxygen composition in the organic compound is_____.[nearest integer]
Given below are two statements.
Statement I: Iron (III) catalyst, acidified \(K_2Cr_2O_7\) and neutral \(KMnO_4\) have the ability to oxidise \(I^–\) to \(I_2\) independently.
Statement II: Manganate ion is paramagnetic in nature and involves \(pπ – pπ\) bonding.
In the light of the above statements, choose the correct answer from the options given below.
The minimum uncertainty in the speed of an electron in an one dimensional region of length 2a0 (Where a0 = Bohr radius 52.9 pm) is _____ km s–1.
(Given : Mass of electron = 9.1 × 10–31 kg, Planck’s constant h = 6.63 × 10–34Js)

In the given conversion the compound A is:

In a cell, the following reactions take place
\(Fe^{2+} → Fe^{3+} + e^-\)
\(E°_{Fe^{3+}/Fe^{2+}} = 0.77\ V\)
\(2I^- → I_2 + 2e^-\)
\(E_{I_2/I^-} = 0.54\ V\)
The standard electrode potential for the spontaneous reaction in the cell is \(x×10^{–2} V\) at \(208\ K\). The value of \(x\) is _______. (Nearest Integer)
In a solid AB, A atoms are in ccp arrangement and B atoms occupy all the octahedral sites. If two atoms from the opposite faces are removed, then the resultant stoichiometry of the compound is AxBy. The value of x is _____. [nearest integer]

Catalyst A reduces the activation energy for a reaction by 10 kJ mol–1 at 300 K. 
The ratio of rate constants,
\(\frac{Κ′ , Catalysed}{Κ,Uncatalysed}\)
is ex. The value of x is ____.[nearest integer]
[Assume that the pre-exponential factor is same in both the cases Given R = 8.31 J K–1 mol–1]

A 42.12% (w, v) solution of NaCl causes precipitation of a certain sol in 10 hours. The coagulating value of NaCl for the sol is
[Given : Molar mass : Na = 23.0 g mol–1; Cl = 35.5 g mol–1]
Amongst baking soda, caustic soda and washing soda, carbonate anion is present in
The correct decreasing order for metallic character is
Which of the following statements are correct?
  1. The electronic configuration of Cr is [Ar] 3d54s1.
  2. The magnetic quantum number may have a negative value.
  3. In the ground state of an atom, the orbitals are filled in order of their increasing energies.
  4. The total number of nodes are given by n – 2.
Choose the most appropriate answer from the options given below :
The acid that is believed to be mainly responsible for the damage of Taj Mahal is

With respect to the following reaction, consider the given statements:

Fig








(A) o-Nitroaniline and p-nitroaniline are the predominant products.
(B) p-Nitroaniline and m-nitroaniline are the predominant products.
(C) HNO3 acts as an acid.
(D) H2SO4 acts as an acid.
Choose the correct option.

Match List I with List II
 List I (polymer) List-II (Nature)
A.
 
A.
I.
Thermosetting polymer
B.
B.
II.
Fibers
C.
C.
III.
Elastomer
D.
D.
IV.Thermoplastic polymer
Choose the correct answer from the options given below:
The correct decreasing order of energy for the orbitals having, following set of quantum numbers:
(A) n = 3, l = 0, m = 0
(B) n = 4, l = 0, m = 0
(C) n = 3, l = 1, m = 0
(D) n = 3, l = 2, m = 1