List of top Chemistry Questions asked in JEE Main

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.

An organic compound ‘A’ contains nitrogen and chlorine. It dissolves readily in water to give a solution that turns litmus red. Titration of compound ‘A’ with standard base indicates that the molecular weight of ‘A’ IS 131±2. When a sample of ‘A’ is treated with aq. NaOH, a liquid separates which contains N but not Cl. Treatment of the obtained liquid with nitrous acid followed by phenol gives orange precipitate. The compound A is :

Consider the above reaction, the compound ‘A’ is :

The molar heat capacity for an ideal gas at constant pressure is 20.785 J K^–1 mol^–1. The change in internal energy is 5000 J upon heating it from 300 K to 500 K. The number of moles of the gas at constant volume is _____. (Nearest integer)
(Given : R = 8.314 JK-1mol-1).

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, \(N_A\) = \(6.022 × 1023\) \(mol^{–1}\))

\(\dot Cl + CH_4 → A + B\)
A and B in the above atmospheric reaction step are:

\(2\ g\) of a non-volatile non-electrolyte solute is dissolved in \(200\ g\) of two different solvents A and B whose ebullioscopic constants are in the ratio of \(1:8\). The elevation in boiling points of A and B are in the ratio \(\frac xy\ (x : y)\). The value of \(y\) is ______ . (Nearest Integer)

For the reaction taking place in the cell:
Pt(s) | H₂(g) | H⁺ (q) || Ag⁺(aq) | Ag(s),
E^o_cell = + 0.5332 V.
The value of Δ_fG^o is _____kJ mol–1 [in nearest integer]

During halogen test, sodium fusion extract is boiled with concentrated HNO₃ to

Given below are two statements:
Statement I : According to the Ellingham diagram, any metal oxide with higher ΔG° is more stable than the one with lower ΔG°.
Statement II :The metal involved in the formation of oxide placed lower in the Ellingham diagram can reduce the oxide of a metal placed higher in the diagram.
In the light of the above statements, choose the most appropriate answer from the options given below

The product formed in the following reaction.

Among the following ores Bauxite, Siderite, Cuprite, Calamine, Haematite, Kaolinite, Malachite, Magnetite, Sphalerite, Limonite, Cryolite, the number of principal ores of iron is____.

A rigid nitrogen tank stored inside a laboratory has a pressure of 30 atm at 06:00 am when the temperature is 27°C. At 03:00 pm, when the temperature is 45°C, the pressure in the tank will be _______ atm. [nearest integer]

The standard entropy change for the reaction \(4Fe(s) + 3O_2(g) → 2Fe_2O_3(s)\) is \(–550\ J K^{–1}\) at \(298\ K\). The temperature in K at which the reaction attains equilibrium is ______. (Nearest Integer)
[Given: The standard enthalpy change for the reaction is \(–165\ kJmol^{–1}\)].

The number of radial and angular nodes in 4d orbital are, respectively

Metal deficiency defect is shown by \(Fe_{0.93}O\). In the crystal, some \(Fe^{2+}\) cations are missing and loss of positive charge is compensated by the presence of \(Fe^{3+}\) ions. The percentage of \(Fe^{2+}\) ions in the \(Fe_{0.93}O\) crystals is ______ . (Nearest integer)

Match List-I with List-II.

	List I		List II
A.	Concentration of	i	Aniline
B.	Leaching of alumina	ii	NaOH
C.	Froth stabilizer	iii	\(SO_2\)
D.	Blister copper	iv	NaCN

Choose the correct answer from the options given below.

\(BeCl_2\) reacts with \(LiAlH_4\) to give:

The dark purple colour of \(KMnO_4\) disappears in the titration with oxalic acid in acidic medium. The overall change in the oxidation number of manganese in the reaction is :

In the following structures, which one is having staggered conformation with maximum dihedral angle?

Consider the above reaction sequence, the product ‘C’ is

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: A mixture contains benzoic acid and naphthalene. The pure benzoic acid can be separated out by the use of benzene.

Reason R: Benzoic acid is soluble in hot water.

In the light of the above statements, choose the most appropriate answer from the options given below.