List of top Chemistry Questions asked in JEE Main

The total number of species from the following in which one unpaired electron is present, is ____.
\[ \text{N}_2, \text{O}_2, \text{C}_2^{-}, \text{O}_2^{-}, \text{H}_2^{+}, \text{CN}^{-}, \text{He}_2^{+} \]

When equal volume of 1M HCl and 1M H$_2$SO$_4$ are separately neutralized by excess volume of 1M NaOH solution, X and Y kJ of heat is liberated respectively. The value of Y/X is ____.

How many compounds among the following compounds show inductive, mesomeric as well as hyperconjugation effects?

Number of colourless lanthanoid ions among the following is ____.
\[ \text{Eu}^{3+}, \, \text{Lu}^{3+}, \, \text{Nd}^{3+}, \, \text{La}^{3+}, \, \text{Sm}^{3+} \]

Number of ambidentate ligands among the following is ____.
\[ \text{NO}_2^{-}, \text{SCN}^{-}, \text{C}_2\text{O}_4^{2-}, \text{NH}_3, \text{CN}^{-}, \text{SO}_4^{2-}, \text{H}_2\text{O} \]

Molarity (M) of an aqueous solution containing \(x \, \text{g}\) of anhyd. CuSO$_4$ in 500 mL solution at 32$^\circ$C is \(2 \times 10^{-1} \, \text{M}\). Its molality will be ____ \( \times 10^{-3} \, \text{m}\) (nearest integer).
[Given density of the solution = 1.25 g/mL.]

On reaction of Lead Sulphide with dilute nitric acid which of the following is not formed ?

Identify the product A and product B in the following set of reactions.

The heat of solution of anhydrous CuSO$_4$ and CuSO$_4\cdot$5H$_2$O are $-70$ kJ mol$^{-1}$ and $+12$ kJ mol$^{-1}$ respectively. The heat of hydration of CuSO$_4$ to CuSO$_4\cdot$5H$_2$O is $-x$ kJ. The value of $x$ is _____.

Identify the incorrect statements regarding primary standard of titrimetric analysis
(A) It should be purely available in dry form.
(B) It should not undergo chemical change in air.
(C) It should be hygroscopic and should react with another chemical instantaneously and stoichiometrically.
(D) It should be readily soluble in water.
(E) KMnO4 & NaOH can be used as primary standard.
Choose the correct answer from the options given below :

Given below are two statements:
Statement I: The rate law for the reaction \[ \text{A + B} \rightarrow \text{C} \] is rate\(({r}) = k[{A}]^2[{B}]\). When the concentration of both A and B is doubled, the reaction rate is increased ``x'' times.
Statement II:

The figure is showing ``the variation in concentration against time plot'' for a ``y'' order reaction. The value of $x + y$ is _________.

0.05M CuSO$_4$ when treated with 0.01M K$_2$Cr$_2$O$_7$ gives green colour solution of Cu$_2$Cr$_2$O$_7$. The \[ \text{[SPM : Semi Permeable Membrane]} \]

\(K_2Cr_2O_7\)		\(CuSO_4\)
Side X	SPM	Side Y

Due to osmosis:

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Both rhombic and monoclinic sulphur exist as S$_8$ while oxygen exists as O$_2$.
{Reason (R): Oxygen forms $p\pi$-$p\pi$ multiple bonds with itself and other elements having small size and high electronegativity like C, N, which is not possible for sulphur.
In the light of the above statements, choose the most appropriate answer from the options given below:

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The total number of geometrical isomers shown by [Co(en)$_2$Cl$_2$]$^+$ complex ion is three.
Reason (R): [Co(en)$_2$Cl$_2$]$^+$ complex ion has an octahedral geometry.
In the light of the above statements, choose the most appropriate answer from the options given below:

Identify major product "X" formed in the following reaction :

What is the structure of C ?

The electronic configuration of Cu(II) is 3d⁹ whereas that of Cu(I) is 3d¹⁰. Which of the following is correct ?

In which one of the following pairs the central atoms exhibit sp$^2$ hybridization?

Given below are two statements:
Statement (I): The oxidation state of an element in a particular compound is the charge acquired by its atom on the basis of electron gain enthalpy consideration from other atoms in the molecule.
Statement (II): $p\pi$-$p\pi$ bond formation is more prevalent in second period elements over other periods.
In the light of the above statements, choose the {most appropriate answer from the options given below:

The F$^-$ ions make the enamel on teeth much harder by converting hydroxyapatite (the enamel on the surface of teeth) into much harder fluoroapatite having the formula:

Methods used for purification of organic compounds are based on :

In the following sequence of reaction, the major products B and C respectively are :

The molar conductivity for electrolytes A and B are plotted against C^1/2 as shown below. Electrolytes A and B respectively are :

The heat of combustion of solid benzoic acid at constant volume is \(-321.30 \, \text{kJ}\) at \(27^\circ \text{C}\). The heat of combustion at constant pressure is \((-321.30 - xR)\, \text{kJ}\). The value of \(x\) is:

Consider the given chemical reaction sequence :

Total sum of oxygen atoms in Product A and Product B are .........