List of top Chemistry Questions asked in JEE Main

The correct match between Item - I and Item - II is :

Item - I	Item - II
(a) Natural rubber	(I) 1, 3-butadiene + styrene
(b) Neoprene	(II) 1, 3-butadiene + acrylonitrile
(c) Buna-N	(III) Chloroprene
(d) Buna-S	(IV) Isoprene

The reaction of NO with \(\mathrm{N_2O_4}\) at 250 K gives :

Which of the following compounds can be prepared in good yield by Gabriel phthalimide synthesis?

The element that can be refined by distillation is :

Match the following compounds (Column-I) with their uses (Column-II) :

S.No.	Column-I	S.No.	Column-II
(I)	\(\mathrm{Ca(OH)_2}\)	(A)	casts of statues
(II)	NaCl	(B)	white wash
(III)	\(\mathrm{CaSO_4,\ \frac{1}{2}H_2O}\)	(C)	antacid
(IV)	\(\mathrm{CaCO_3}\)	(D)	washing soda preparation

The IUPAC name of the following compound is :

The average molar mass of chlorine is 35.5 g mol\(^{-1}\). The ratio of \(^{35}\mathrm{Cl}\) to \(^{37}\mathrm{Cl}\) in naturally occuring chlorine is close to :

A set of solutions is prepared using 180 g of water as a solvent and 10 g of different nonvolatile solutes A, B and C. The relative lowering of vapour pressure in the presence of these solutes are in the order :
[Given, molar mass of A = 100 g mol\(^{-1}\); B = 200 g mol\(^{-1}\); C = 10,000 g mol\(^{-1}\)]

The increasing order of the boiling points of the major products A, B and C of the following reactions will be :

Match the following :

Test/Method	Reagent
(i) Lucas Test	(a) \(\mathrm{C_6H_5SO_2Cl}\)/ aq. KOH
(ii) Dumas method	(b) \(\mathrm{HNO_3}\)/ \(\mathrm{AgNO_3}\)
(iii) Kjeldahl's method	(c) \(\mathrm{CuO/CO_2}\)
(iv) Hinsberg test	(d) Conc. HCl and \(\mathrm{ZnCl_2}\)
	(e) \(\mathrm{H_2SO_4}\)

Mischmetal is an alloy consisting mainly of :

For the given cell :
\(\mathrm{Cu(s)\,|\,Cu^{2+}(C_1\,M)\,||\,Cu^{2+}(C_2\,M)\,|\,Cu(s)}\)
change in Gibbs energy (\(\Delta G\)) is negative, if :

Which one of the following statements is not true?

The value of \(K_C\) is 64 at 800 K for the reaction
\(\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}\)
The value of \(K_C\) for the following reaction is :
\(\mathrm{NH_3(g) \rightleftharpoons \frac{1}{2}N_2(g) + \frac{3}{2}H_2(g)}\)

The correct match between Item-I (starting material) and Item-II (reagent) for the preparation of benzaldehyde is :

Item-I	Item-II
(I) Benzene	(P) HCl and \(\mathrm{SnCl_2}\), \(\mathrm{H_3O^+}\)
(II) Benzonitrile	(Q) \(\mathrm{H_2}\), Pd-\(\mathrm{BaSO_4}\), S and quinoline
(III) Benzoyl Chloride	(R) CO, HCl and \(\mathrm{AlCl_3}\)

For a \(\mathrm{d^4}\) metal ion in an octahedral field, the correct electronic configuration is :

For a reaction,
\(4\mathrm{M(s)}+n\mathrm{O_2(g)}\rightarrow2\mathrm{M_2O_n(s)}\)
the free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which :

In an estimation of bromine by Carius method, 1.6 g of an organic compound gave 1.88 g of AgBr. The mass percentage of bromine in the compound is ______.
(Atomic mass, Ag = 108, Br = 80 g \(\mathrm{mol^{-1}}\))

The elevation of boiling point of 0.10 m aqueous \(\mathrm{CrCl_3 \cdot xNH_3}\) solution is two times that of 0.05 m aqueous \(\mathrm{CaCl_2}\) solution. The value of x is ______.

[Assume 100% ionisation of the complex and \(\mathrm{CaCl_2}\), coordination number of Cr as 6, and that all \(\mathrm{NH_3}\) molecules are present inside the coordination sphere]

Potassium chlorate is prepared by the electrolysis of KCl in basic solution

\(6\mathrm{OH^-} + \mathrm{Cl^-} \to \mathrm{ClO_3^-} + 3\mathrm{H_2O} + 6e^-\)

If only 60% of the current is utilized in the reaction, the time (rounded to the nearest hour) required to produce 10 g of \(\mathrm{KClO_3}\) using a current of 2 A is ______.

(Given : F = 96,500 C \(\mathrm{mol^{-1}}\); molar mass of \(\mathrm{KClO_3}\) = 122 g \(\mathrm{mol^{-1}}\))

A spherical balloon of radius 3 cm containing helium gas has a pressure of \(48 \times 10^{-3}\) bar. At the same temperature, the pressure, of a spherical balloon of radius 12 cm containing the same amount of gas will be ______ \(\times 10^{-6}\) bar.

Consider the Assertion and Reason given below.

Assertion (A) : Ethene polymerized in the presence of Ziegler Natta Catalyst at high temperature and pressure is used to make buckets and dustbins.

Reason (R) : High density polymers are closely packed and are chemically inert.

Choose the correct answer from the following:

The presence of soluble fluoride ion upto 1 ppm concentration in drinking water, is :

Among the sulphates of alkaline earth metals, the solubilities of BeSO₄ and MgSO₄ in water, respectively, are :

The number of Cl = O bonds in perchloric acid is, "________".