List of top Chemistry Questions asked in JEE Main

For the following Assertion and Reason, the correct option is

Assertion (A): When Cu (II) and sulphide ions are mixed, they react together extremely quickly to give a solid.

Reason (R): The equilibrium constant of \(\mathrm{Cu^{2+}(aq) + S^{2-}(aq) \rightleftharpoons CuS(s)}\) is high because the solubility product is low.

Which of the following compunds will show retention in configuration on nucleophilic substitution by \(\mathrm{OH^-}\) ion?

A sample of milk splits after 60 min. at 300 K and after 40 min. at 400 K when the population of lactobacillus acidophilus in it doubles. The activation energy (in kJ/mol) for this process is closest to__________.
(Given, \(R = 8.3\ \mathrm{J\ mol^{-1}\ K^{-1}}\), \(\ln\left(\frac{3}{2}\right) = 0.4\), \(e^{-3} = 4.0\))

10.30 mg of \(\mathrm{O_2}\) is dissolved into a liter of sea water of density 1.03 g/mL. The concentration of \(\mathrm{O_2}\) in ppm is__________.

The sum of the total number of bonds between chromium and oxygen atoms in chromate and dichromate ions is ____________.

Which polymer has 'chiral' monomer(s) ?

Amongst the following, the form of water with the lowest ionic conductance at 298 K is :

The isomer(s) of \(\mathrm{[Co(NH_3)_4Cl_2]}\) that has/have a Cl-Co-Cl angle of 90\(^\circ\), is/are :

Which of the following has the shortest C-Cl bond?

The reaction of \(\mathrm{H_3N_3B_3Cl_3}\) (A) with \(\mathrm{LiBH_4}\) in tetrahydrofuran gives inorganic benzene (B). Further, the reaction of (A) with (C) leads to \(\mathrm{H_3N_3B_3(Me)_3}\). Compounds (B) and (C) respectively, are :

5 g of zinc is treated separately with an excess of
(a) dilute hydrochloric acid and
(b) aqueous sodium hydroxide.
The ratio of the volumes of \(\mathrm{H_2}\) evolved in these two reactions is :

A, B and C are three biomolecules. The results of the tests performed on them are given below:

	Molisch's Test	Barfoed Test	Biuret Test
A	Positive	Negative	Negative
B	Positive	Positive	Negative
C	Negative	Negative	Positive

A, B and C are respectively :

The first and second ionisation enthalpies of a metal are 496 and 4560 kJ mol\(^{-1}\), respectively. How many moles of HCl and \(\mathrm{H_2SO_4}\), respectively, will be needed to react completely with 1 mole of the metal hydroxide ?

The molarity of \(\mathrm{HNO_3}\) in a sample which has density 1.4 g/mL and mass percentage of 63% is _____.
(Molecular Weight of \(\mathrm{HNO_3}\) = 63)

The hardness of a water sample containing \(10^{-3}\) M \(\mathrm{MgSO_4}\) expressed as \(\mathrm{CaCO_3}\) equivalents (in ppm) is ______.
(molar mass of \(\mathrm{MgSO_4}\) is 120.37 g/mol)

A chemist has 4 samples of artificial sweetener A, B, C and D. To identify these samples, he performed certain experiments and noted the following observations :
(i) A and D both form blue-violet colour with ninhydrin.
(ii) Lassaigne extract of C gives positive \(\mathrm{AgNO_3}\) test and negative \(\mathrm{Fe_4[Fe(CN)_6]_3}\) test.
(iii) Lassaigne extract of B and D gives positive sodium nitroprusside test
Based on these observations which option is correct ?

\([\mathrm{Pd(F)(Cl)(Br)(I)}]^{2-}\) has n number of geometrical isomers. Then, the spin-only magnetic moment and crystal field stabilisation energy [CFSE] of \([\mathrm{Fe(CN)_6}]^{n-6}\), respectively, are:
[Note : Ignore the pairing energy]

The acidic, basic and amphoteric oxides, respectively, are :

The compound that cannot act both as oxidising and reducing agent is :

The \(K_{sp}\) for the following dissociation is \(1.6 \times 10^{-5}\)
\(\mathrm{PbCl_{2(s)} \rightleftharpoons Pb^{2+}_{(aq)} + 2Cl^-_{(aq)}}\)
Which of the following choices is correct for a mixture of 300 mL 0.134 M \(\mathrm{Pb(NO_3)_2}\) and 100 mL 0.4 M NaCl ?

B has a smaller first ionization enthalpy than Be. Consider the following statements :
(I) It is easier to remove 2p electron than 2s electron
(II) 2p electron of B is more shielded from the nucleus by the inner core of electrons than the 2s electrons of Be.
(III) 2s electron has more penetration power than 2p electron.
(IV) atomic radius of B is more than Be (Atomic number B = 5, Be = 4)
The correct statements are :

If the magnetic moment of a dioxygen species is 1.73 B.M, it may be :

Complexes (\(\mathrm{ML_5}\)) of metals Ni and Fe have ideal square pyramidal and trigonal bipyramidal grometries, respectively. The sum of the \(90^\circ\), \(120^\circ\) and \(180^\circ\) L-M-L angles in the two complexes is _________.

\(\mathrm{NaClO_3}\) is used, even in spacecrafts, to produce \(\mathrm{O_2}\). The daily consumption of pure \(\mathrm{O_2}\) by a person is 492 L at 1 atm, 300 K. How much amount of \(\mathrm{NaClO_3}\), in grams, is required to produce \(\mathrm{O_2}\) for the daily consumption of a person at 1 atm, 300 K?
\(\mathrm{NaClO_3(s) + Fe(s) \to O_2(g) + NaCl(s) + FeO(s)}\)
\(R = 0.082\ \mathrm{L\ atm\ mol^{-1}\ K^{-1}}\)

Preparation of Bakelite proceeds via reactions.