List of top Chemistry Questions asked in JEE Main

Amongst the following, the number of oxide(s) which are paramagnetic in nature is
Na₂O, KO₂, NO₂, N₂O, ClO₂, NO, SO₂, Cl₂O

The equation k = (6.5 × 10¹²s^–1)e^–26000K/T is followed for the decomposition of compound A. The activation energy for the reaction is ______ kJ mol^–1. [nearest integer]
(Given : R = 8.314 J K^–1 mol^–1]

The cell potential for the given cell at 298 K \(\text{Pt} | \text{H}_2 \text{(g, 1 bar)} | \text{H}^+ \text{(aq)} || \text{Cu}^{2+} \text{(aq)} | \text{Cu(s)}\) is 0.31 V. The pH of the acidic solution is found to be 3, whereas the concentration of Cu²⁺ is 10^–x M. The value of x is _____.
(Given : \(E^{Θ}_{Cu^{2+}/Cu}\) = 0.34 V and \(\frac{2.303RT}{F}\) = 0.06 V)

Hex-4-ene-2-ol on treatment with PCC gives ‘A’ on reaction with sodium hypoiodite gives ‘B’, which on further heating with soda lime gives ‘C’. The compound ‘C’ is

Number of complexes which will exhibit synergic bonding amongst, \([Cr(CO)_6]\), \([Mn(CO)_5]\) and \([Mn_2(CO)_{10}]\) is ________.

Some gases are responsible for heating of atmosphere (green house effect). Identify from the following the gaseous species which does not cause it.

When sugar ‘X’ is boiled with dilute H2SO4 in alcoholic solution, two isomers ‘A’ and ‘B’ are formed. ‘A’ on oxidation with HNO3 yields saccharic acid whereas ‘B’ is laevorotatory. The compound ‘X’ is :

\(PCl_5\) dissociates as
\(PCl_5(g) ⇌ PCl_3(g)+ Cl_2(g)\)
\(5\) moles of \(PCl_5\) are placed in a \(200\) litre vessel which contains \(2\) moles of \(N_2\) and is maintained at \(600\ K\). The equilibrium pressure is \(2.46\) atm. The equilibrium constant Kp for the dissociation of \(PCl_5\) is ______ \(× 10^{–3}\). (nearest integer)
(Given: \(R = 0.082\) L atm K^–1 mol^–1; Assume ideal gas behaviour)

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

Assertion A : Magnesium can reduce Al₂O₃ at a temperature below 1350°C, while above 1350°C aluminium can reduce MgO.
Reason R : The melting and boiling points of magnesium are lower than those of aluminium.

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

A primary aliphatic amine on reaction with nitrous acid in cold (273 K) and there after raising temperature of reaction mixture to room temperature (298 K), gives

The products obtained during treatment of hard water using Clark’s method are:

Two isomers (A) and (B) with Molar mass 184 g/mol and elemental composition C, 52.2%; H, 4.9 % and Br 42.9% gave benzoic acid and p-bromobenzoic acid, respectively on oxidation with KMnO₄. Isomer ‘A’ is optically active and gives a pale yellow precipitate when warmed with alcoholic AgNO₃. Isomers ‘A’ and ‘B’ are, respectively.

In Carius method of estimation of halogen, 0.45 g of an organic compound gave 0.36 g of AgBr. Find out the percentage of bromine in the compound.
(Molar masses: AgBr = 188 g mol^–1; Br = 80 g mol^–1)

What will be the major product of the following sequence of reactions?
\(n−Bu−≡ \xrightarrow[{(ii)Lindlar catalyst, H_2}]{(i)n-BuLi,n-C_5H_{11}Cl}\)

Borazine, also known as inorganic benzene, can be prepared by the reaction of 3-equivalents of “X” with 6-equivalents of “Y”. “X” and “Y”, respectively are:

Consider the following reaction:
A + alkali → B (Major Product)
If B is an oxoacid of phosphorus with no P-H bond, then A is

The correct order of reduction potentials of the following pairs is

(A)\( \frac{Cl_2}{Cl^–}\)

(B)\( \frac{I_2}{I^–}\)

(C) \(\frac{Ag^+}{Ag}\)

(D) \(\frac{Na^+}{Na}\)

(E) \(\frac{Li^+}{ Li}\)

Choose the correct answer from the options given below:

Dinitrogen and dioxygen, the main constituents of air do not react with each other in atmosphere to form oxides of nitrogen because

Match List I with List II.

List I Pollutant	List II Disease/ sickness
A. Sulphate (> 500 ppm)	I. Methemoglobinemia
B. Nitrate (> 50 ppm)	II. Brown mottling of teeth
C. Lead (> 50 ppb)	III. Laxative effect
D. Fluoride (> 2ppm)	IV. Kidney damage

Choose the coned answer from the options given below: