List of top Chemistry Questions asked in JEE Main

Match the following:

CaCO$₃$(s) $\rightleftharpoons$ CaO(s) + CO$₂$(g), \( K_{p1} = 8 \times 10^{-2} \)
C(s) + CO$₂$(g) $\rightleftharpoons$ 2CO(g), \( K_{p2} = 2 \)
If the partial pressure of CO at equilibrium is \( x \times 10^{-1} \) atm, then find the value of \( x \).

Statement-I: \( K_b \) is more than \( K_f \) for water.
Statement-II: When we add a non-volatile solute in water, elevation in boiling point is more than depression in freezing point.

Statement-I: 30% (w/w) methanol in CCl₄ have mole fraction of solvent equal to 0.33.
Statement-II: CCl₄ and methanol mixture show positive deviation from Raoult's law.

Wavelengths of two photons are given as \(\lambda_1 = 3000 \, \text{Å}\) and \(\lambda_2 = 6000 \, \text{Å}\) respectively. Calculate the ratio of their energies \(\left( \frac{E_1}{E_2} \right)\).

Calculate the equilibrium constant for the following equilibrium:
\[ \frac{1}{2} X_2 + \frac{1}{2} Y_2 \rightleftharpoons XYZ \] Given: \[ 2XY \rightleftharpoons X_2 + Y_2, \quad K_1 = 2.5 \times 10^{-5} \] \[ \frac{1}{2} Z_2 + XY \rightleftharpoons XYZ, \quad K_2 = 5 \times 10^{-3} \]

\( E^0_{\text{Fe}^{2+}/\text{Fe}} \) / Fe = x volts, \( E^0_{\text{Fe}^{3+}/\text{Fe}^{2+}} \) = y volts.
Calculate \( E^0_{\text{Fe}^{2+}/\text{Fe}^{3+}} \) in volts.

Statement-I: When temperature is increased from 298 K to 308 K, having \( E_a = 12.72 \, \text{Kcal mol}^{-1} \), Rate constant (K) is doubled.
Statement-II: For a first (1st) order reaction \( A \rightarrow B \), the following graph is valid.

Calculate \(|\Delta H^{\circ}|\) for the following reaction (in kJ/mol):
\[ 2H_2S(g) + 3O_2(g) \rightarrow 2SO_2(g) + 2H_2O(l) \] Given data: \[ \Delta H_f^{\circ}(H_2S(g)) = -20.6 \, \text{kJ/mol}, \Delta H_f^{\circ}(SO_2(g)) = -296.8 \, \text{kJ/mol}, \Delta H_f^{\circ}(H_2O(l)) = -285.8 \, \text{kJ/mol} \]

Sucrose hydrolyses in acidic medium into glucose and fructose by first order rate law with $t_{1/2} = 3$ hour. The percentage of sucrose remaining after 6 hours is ______. (Nearest integer)
(Given : $\log 2 = 0.3010$ and $\log 3 = 0.4771$)

Consider the reaction $X \rightleftharpoons Y$ at $300$ K. If $\Delta H^{\theta}$ and $K$ are $28.40$ kJ mol$^{-1}$ and $1.8 \times 10^{-7}$ at the same temperature, then the magnitude of $\Delta S^{\theta}$ for the reaction in J K$^{-1}$ mol$^{-1}$ is ______. (Nearest integer)
(Given : $R = 8.3$ J K$^{-1}$ mol$^{-1}$, $\ln 10 = 2.3$, $\log 3 = 0.48$, $\log 2 = 0.30$)

4.7 g of phenol is heated with Zn to give product X. If this reaction goes to 60% completion then the number of moles of compound X formed will be ________ $\times 10^{-2}$. (Nearest Integer)
(Given molar mass in $\text{g mol}^{-1}$ : H:1, C:12, O:16)

Consider the following sequence of reactions.

The percentage of nitrogen in the yellow product (X) formed is ________ %. (Nearest Integer)
(Given Molar mass in $\text{g mol}^{-1}$ H:1, C:12, N:14)

Arrange the following compounds according to increasing order of boiling points.
n-$C_4H_9OH$ (A), n-$C_4H_9NH_2$ (B), n-$C_4H_{10}$ (C) and $C_2H_5NHC_2H_5$ (D).

Match the LIST-I with LIST-II.

Choose the correct answer from the options given below:

First and second ionization enthalpies of lithium are $520\text{ kJ mol}^{-1}$ and $7297\text{ kJ mol}^{-1}$ respectively. Energy required to convert $3.5\text{ mg}$ lithium (g) into $\text{Li}^{2+}(g)$ $[\text{Li}(g) \rightarrow \text{Li}^{2+}(g)]$ is ________ $\text{kJ mol}^{-1}$. (nearest integer)
[Molar mass of $\text{Li} = 7\text{ g mol}^{-1}$]

Match the LIST-I with LIST-II.

Choose the correct answer from the options given below:

Given below are two statements:

Statement I: Methane can be prepared by decarboxylation of sodium ethanoate, Kolbe's electrolysis of sodium acetate and reaction of $CH_3MgBr$ with water.
Statement II: Methane cannot be prepared from unsaturated hydrocarbons and by Wurtz reaction.

In the light of the above statements, choose the correct answer from the options given below

Given below are two statements:

Statement I: 3-phenylpropene reacts with $HBr$ and gives secondary alkyl bromide having a chiral carbon atom as the major product.

Statement II: Aryl chlorides and aryl cyanides can be prepared by Sandmeyer reaction as well as Gattermann reaction.

In the light of the above statements, choose the correct answer from the options given below

Which of the following are true about the energy of the given d-orbitals of a tetrahedral complex?

A. $d_{xy} = d_{yz}>d_{x^2-y^2}$
B. $d_{xy} = d_{yz}>d_{z^2}$
C. $d_{x^2-y^2}>d_{z^2}>d_{xz}$
D. $d_{x^2-y^2} = d_{z^2}<d_{xz}$

Given below are two statements:

Statement I: 2,6-diethylcyclohexanone and 6-methyl-2-n-propylcyclohexanone are metamers.
Statement II: 2,2,6,6 - tetramethylcyclohexanone exhibits keto-enol tautomerism.

In the light of the above statements, choose the correct answer from the options given below

$R_f$ value for 2-methylpropene in a solvent system (Ethyl acetate + ether) is 0.42. 2-methylpropene is treated with dilute $H_2SO_4$ to give major organic product (X). $R_f$ value for (X) in the same solvent system under identical condition will be:

Given below are two statements:

Statement I: Aluminium is more electropositive than thallium as the standard electrode potential value of $E^\circ_{Al^{3+}/Al}$ is negative and $E^\circ_{Tl^{3+}/Tl}$ is positive.
Statement II: The sum of first three ionization enthalpies of boron is very high when compared to that of aluminium. Due to this reason boron forms covalent compounds only and aluminium forms $Al^{3+}$ ion.

In the light of the above statements, choose the correct answer from the options given below