List of top Chemistry Questions asked in JEE Main

The correct IUPAC nomenclature of the following compound is:

A cycloalkene (X) is treated with Br\(_2\) and compound (Y) is formed with C : Br ratio 3 : 1. One mole of X required 1 mol of Br\(_2\). Find the composition of 'Br' in Y compound (percentage).

Consider the following statements:

[(A)] \(\mathrm{KMnO_4}\) is diamagnetic while \(\mathrm{K_2MnO_4}\) is paramagnetic.
[(B)] Manganate ion contains \(\mathrm{Mn^{6+}}\) while permanganate ion contains \(\mathrm{Mn^{7+}}\).
[(C)] \(\mathrm{Mn^{2+}}\) ion on reaction with \(\mathrm{S_2O_8^{2-}}\) ions gives manganate ion.
[(D)] Both \(\mathrm{MnO_4^-}\) and \(\mathrm{MnO_4^{2-}}\) are tetrahedral.
Correct statements are:

Out of \( \mathrm{N, P, S, Cl, F} \), number of valence electrons in the {least metallic element and most metallic element respectively is: }

Two positively charged particles are accelerated by \(200\,\text{keV}\). The masses of particles are \(m_1 = 1\,\text{amu}\) and \(m_2 = 4\,\text{amu}\).

If the de-Broglie wavelength \((\lambda_d)_{m_1}\) is \(x\) times of the second particle \((\lambda_d)_{m_2}\), determine the value of \(x\).

In carius method of estimation of 'Br' 1.53 gm of an organic compound gave 1 gm AgBr. The % of Br in organic compound is (At. mass of Ag and Br are 108 and 80 amu respectively)

Statement-I : Test for nitrite; sulphanilic acid and 1-napthylamine are used.
Statement-II : Acidified nitrite is di-azotized with sulphanilic acid and coupled with 1-napthylamine.
Select the correct statement.

In $4^{\text{th}}$ period of periodic table the elements with the largest and smallest size respectively is :

Calculate pH of 10 mM weak acid (HA) dissociated in water. Assume $\alpha$ to be negligible. Given $\text{pK}_a = 4$

Select incorrect option:

Correct order of 2$^{nd}$ ionisation energy is:

0.18 M HQ solution has molar conductivity $\frac{1}{30}$ times the molar conductivity of 0.02 M HZ solution. Find the value of pK$_a$(HQ) − pK$_a$(HZ).
[Given that $\alpha$ is very less than 1]

In general tests of Ba$^{2+}$ and Ca$^{2+}$ give the respective tests as:

The half-life of radioactive isotope Zn$^{65}$ is 245 days. Find the time after which activity of Zn sample remains 75% of its initial value.

Statement-I: Two different aldehydes on cross aldol condensation always give four products.
Statement-II: Among benzaldehyde and acetophenone, only acetophenone reacts with semicarbazide.

Element X is the lightest element of group 7 of periodic table which forms oxo-anion in +6 oxidation state. The colour of potassium salt of the oxo-anion is:

Sodium extract of organic compound of 0.1 g is treated with chlorine water and \( \text{CCl}_4 \) which dissolves in organic solvent to produce a violet colour. Upon treatment with \( \text{AgNO}_3 \), a yellow ppt. of 0.12 g is produced. Calculate the percentage of halide in the organic compound.

For a given reaction, K$_p$ = 9 atm
NH$_3$(g) $\longrightarrow$ $\frac{1}{2}$ N$_2$(g) + $\frac{3}{2}$ H$_2$(g)
Total pressure at equilibrium is $\sqrt{5}$ atm.
Find the value of 7$\alpha^2$, where $\alpha$ is degree of dissociation of NH$_3$(g)

The maximum number of electrons in the following two given set of quantum numbers (i) \( n = 5, \, m_l = -1 \) and (ii) \( n = 4, \, \ell = 2, \, m_l = 1, \, m_s = \frac{1}{2} \) respectively is:

Which of the following is correct match for hydrogen-like species for the total energy of e$^-$?

Which of the following are the compound(s) that do not give Tollen's test?

The correct order of ionization energy of Cl, S, P, Al, Si is: