List of top Chemistry Questions asked in JEE Main

Fig. Chemical Reaction







Consider the above reaction sequence and identify the product B.

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

Haemoglobin contains \(0.34\%\) of iron by mass. The number of Fe atoms in \(3.3\) g of haemoglobin is(Given: Atomic mass of Fe is \(56\) u, \(N_A\) = \(6.022 × 1023\) \(mol^{–1}\))
At 30ºC, the half life for the decomposition of \(AB_2\) is 200 s and is independent of the initial concentration of \(AB_2\). The time required for 80% of the \(AB_2\) to decompose is(Given : \(log\; 2 = 0.30,\; log \;3 = 0.48\))
Given below are two statements: one is labelled as Assertion A and other is labelled as Reason R.
Assertion A : Finest gold is red in colour, as the size of the particles increases, it appears purple then blue and finally gold.
Reason R : The colour of the colloidal solution depends on the wavelength of light scattered by the dispersed particles.
In the light of the above statements, choose the most appropriate answer from the options given below.
The metal that has very low melting point and its periodic position is closer to a metalloid is
Among the following the number of curves not in accordance with Freundlich adsorption isotherm is____.
Number of curves

For a reaction, given below is the graph of ln k vs 1/T. The activation energy for the reaction is equal to____ \(cal mol^{–1}\). (Nearest integer) 

(Given: \(R = 2 cal K^{-1} mol^{-1}\))

Graph In k vs T

During the denaturation of proteins, which of these structures will remain intact ?
Drugs used to bind to receptors, inhibiting its natural function and blocking a message are called :
Given below are two statements:
Statement-I : In Hofmann degradation reaction, the migration of only an alkyl group takes place from carbonyl carbon of the amide to the nitrogen atom.
Statement-II : The group is migrated in Hofmann degradation reaction to electron deficient atom.
In the light of the above statements, choose the most appropriate answer from the options given below:
In the above reaction, 5 g of toluene is converted into benzaldehyde with 92% yield. The amount of benzaldehyde produced is______ × 10–2 g. (Nearest integer).
Consider an imaginary ion \(\\_{22}^{48}X^{3−}\).The nucleus contains ‘a’% more neutrons than the number of electrons in the ion. The value of ‘a’ is ________. [nearest integer
For the reaction H2F2(g) → H2(g) + F2(g), ΔU = –59.6 kJ mol–1 at 27°C. The enthalpy change for the above reaction is (–) _______ kJ mol–1 [nearest integer] Given: R = 8.314 J K–1 mol–1.

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

The spin-only magnetic moment value of the compound with strongest oxidizing ability among MnF4, MnF3 and MnF2 is____ B.M. [nearest integer]
Total number of isomers (including stereoisomers) obtained on monochlorination of methylcyclohexane is____.
How many of the following drugs is/are examples(s) of broad-spectrum antibiotics?
Ofloxacin, Penicillin G, Terpineol, Salvarsan.
The major product in the given reaction is
Question Reaction
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
Match List-I with List -II
List - IList - II
(A) \(ψ_{MO}=ψ_A-ψ_B\)(I) Dipole moment
(B) \(µ=Q×r \)(II) Bonding molecular orbital
(C) \(\frac{N_b-N_a}2\)(III) Anti-bonding molecular orbital
(D) \(ψ_{MO}=ψ_A+ψ_B\)(IV) Bond order

Choose the correct answer from options given below:

When the excited electron of a H atom from n = 5 drops to the ground state, the maximum number of emission lines observed are ____.

Which of the following statement is incorrect?

The number of paramagnetic species among the following is ____B2,Li2,C2,C-2, O22--,O2+ and He2+

Ka for butyric acid (C3H7COOH) is 2 × 10–5. The pH of 0.2 M solution of butyric acid is ______× 10–1. (Nearest integer) (Given log2 = 0.30)