List of top Chemistry Questions asked in JEE Main

Which of the following pairs is not isoelectronic species? 
(At. no. Sm, 62; Er, 68; Yb, 70; Lu, 71; Eu, 63; Tb, 65; Tm, 69)

The activation energy of one of the reactions in a biochemical process is 532611 J mol–1. When the temperature falls from 310 K to 300 K, the change in rate constant observed is k300 = x × 10–3 k310. The value of x is ______.

[Given: ln10 = 2.3, R = 8.3 JK–1 mol–1]

Among the following structures, which will show the most stable enamine formation? 
(Where Me is –CH3)

The polymer, which can be stretched and retains its original status on releasing the force is
Match List-I with List-II
List-I (Compound)List-II (Shape)
(A) \(BrF_5\)(I) bent
(B) \([CrF_6]^{3–}\)(II) square pyramidal
(C) \(O_3\)(III) trigonal bipyramidal
(D) \(PCI_5\)(IV) octahedral
Choose the correct answer from the options given below :
Among the following, basic oxide is:

Match List-I with List-II :
 

List-IList-II
(A) Negatively charged sol(I) Fe2O3.xH2O
(B) Macromolecular colloid(II) CdS sol
(C) Positively charged sol(III) Starch
(D) Cheese(IV) a gel


Choose the correct answer from the options given below:

2.5 g of protein containing only glycine (C2H5NO2) is dissolved in water to make 500 mL of solution. The osmotic pressure of this solution at 300 K is found to be 5.03 × 10–3 bar. The total number of glycine units present in the protein is _______.
(Given : R = 0.083 L bar K–1 mol–1)
The amount of charge in F (Faraday) required to obtain one mole of iron from \(Fe_3O_4\) is ______ . (Nearest integer)

The reagent, from the following, which converts benzoic acid to benzaldehyde in one step is

In the following reaction,
the % yield for reaction I is 60% and that of reaction II is 50%. The overall yield of the complete reaction is _______%. [Nearest integer].

the % yield for reaction I is 60% and that of reaction II is 50%.

Arrange the following coordination compounds in the increasing order of magnetic moments. (Atomic numbers: \(Mn = 25; Fe = 26\))
(1) \([FeF_6]^{3–}\)
(2) \([Fe(CN)_6]^{3–}\)
(3) \([MnCl_6]^{3–}\) (high spin)
(4) \([Mn(CN)_6]^{3–}\)
Vulcanization of rubber is carried out by heating a mixture of
An antiseptic Dettol is a mixture of two compounds ‘A’ and ‘B’ where A has 6π electrons and B has 2π electrons. What is ‘B’?
Which of the following reagents/reactions will convert ‘A’ to ‘B’?
reagents/reactions
The spin-only magnetic moment value of the compound with strongest oxidizing ability among MnF4, MnF3 and MnF2 is____ B.M. [nearest integer]
The intermediate X, in the reaction is:
The intermediate X, in the reaction
17.0 g of NH3 completely vapourises at – 33.42°C and 1 bar pressure and the enthalpy change in the process is 23.4 kJ mol–1 . The enthalpy change for the vapourisation of 85 g of NH3 under the same conditions is ____ kJ.

The major product of the following reaction contains ______ bromine atom(s).

Fig
The number of terminal oxygen atoms present in the product B obtained from the following reaction is ______.
FeCr2O4 + Na2CO3 + O2 → A + Fe2O3 + CO2
A + H+ → B + H2O + Na+
s-block element which cannot be qualitatively confirmed by the flame test is

The number of non-ionisable protons present in the product B obtained from the following reactions is__.
C2H5OH+PCl3→C2H5Cl+A
A+PCl3→B

Amongst the following, the major product of the given chemical reaction is

Amongst the following, the major product of

The conductivity of a solution of complex with formula CoCl3(NH3)4 corresponds to 1 : 1 electrolyte, then the primary valency of central metal ion is ______.
A radioactive element has a half life of 200 days. The percentage of original activity remaining after 83 days is ________. (Nearest integer) (Given : antilog 0.125 = 1.333, antilog 0.693 = 4.93)