List of top Chemistry Questions asked in JEE Main

If for Li$^{2+}$ ion, electron is in transition between energy levels such that sum of principal quantum numbers is 4 and difference is 2, then find the wavelength (in cm) emitted for transition between these energy levels.
[Given: $R = 1.1 \times 10^5\ \text{cm}^{-1}$]
Correct order of 2$^{nd}$ ionisation energy is:
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.
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:
Heat of atomisation of CH$_4$(g) and C$_2$H$_6$(g) are $x$ kJ/mol and $y$ kJ/mol respectively. Find the maximum wavelength of photon required to dissociate C–C bond in C$_2$H$_6$.
Select incorrect option:
Which of the following statement is correct regarding an element having atomic number 79?
For the reaction given below at 25°C: \[ \text{A}_2 \rightleftharpoons 2\text{A} \] Find \( K_p \). Given \( \Delta G^\circ_A = -50.384 \, \text{kJ/mol} \) and \( \Delta G^\circ_{A_2} = -100 \, \text{kJ/mol} \).
Statement-I: Sucrose is dextrorotatory and upon hydrolysis, it becomes laevorotatory. Statement-II: Sucrose on hydrolysis gives glucose and fructose such that the laevorotation of glucose is more than dextrorotation of fructose. Which of the following is correct?
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.
Which of the following statement is correct regarding the nature and directive influence of \( \text{NO}_2 \) group in nitrobenzene?
Which of the following are the compound(s) that do not give Tollen's test?
25 ml, 0.1 M Ba(OH)$_2$ react completely with HCl. Find the weight of HCl (in milligram) required?
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)
Consider the following statements about group 13 elements of the periodic table. (A) Electronegativity decreases down the group.
(B) Size increases down the group.
(C) Ionization energy decreases down the group.
(D) Boiling point of Boron is maximum.
(E) Melting point of Boron is maximum.
Which of the following is correct match for hydrogen-like species for the total energy of e$^-$?
For a given reaction at 400 K (R = 0.082 atm-L/mol-K) \[ xA \longleftrightarrow yB \] Given (i) \(K_f = 0.82\), \(K_c = 25.7\)
(ii) \(K_f = 8.2\), \(K_c = 0.25\)
Then which will be the correct combination of x & y for above set (i) & set (ii) data?
The correct order of ionization energy of Cl, S, P, Al, Si is:
Statement-1: Sublimation is a purification technique that is used to separate those solid substances which change from solid to vapor state without passing through liquid state.
Statement-2: If external atmospheric pressure is reduced, then boiling point of substance decreases.
Which of the following is correct?
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 a basic buffer?

Given below are two statements: 
Statement I: All the pairs of molecules \((\mathrm{PbO}, \mathrm{PbO_2}); (\mathrm{SnO}, \mathrm{SnO_2})\) and \((\mathrm{GeO}, \mathrm{GeO_2})\) contain amphoteric oxides. 
Statement II: \(\mathrm{AlCl_3}, \mathrm{BH_3}, \mathrm{BeH_2}\) and \(\mathrm{NO_2}\) all have incomplete octet. 
In the light of the above statements, choose the correct option.

Consider the following reaction: \[ {Ca + 2HCl → CaCl2 + H2} \] If \(14\,\text{g}\) of calcium reacts with excess \( {HCl} \), choose the {incorrect} option.
\(80\,\text{mL}\) of an organic compound is mixed with \(264\,\text{mL}\) of \(O_2\) and ignited. It gives \(224\,\text{mL}\) of gaseous mixture at NTP. After passing through KOH, \(64\,\text{mL}\) of gas remains. The organic compound is: