List of top Chemistry Questions asked in JEE Main

$R_f$ 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:

One mole each of He and $A(g)$ are taken in a 10 L closed flask and heated to 400 K to establish the following equilibrium.
$$A(g) \rightleftharpoons B(g)$$
$K_c$ for this reaction at 400 K is 4.0. The partial pressures (in atm) of He and $B(g)$ are respectively (at equilibrium)
(Assume He, $A(g)$ and $B(g)$ behave as ideal gases)
(Given : $R = 0.082 \text{ L atm K}^{-1} \text{ mol}^{-1}$)

Consider the following data.

$$\begin{array}{|c|c|} \hline \text{Electrolyte} & \Lambda_m^\circ (\text{S cm}^2 \text{ mol}^{-1}) \\ \hline \text{BaCl}_2 & x_1 \\ \hline \text{H}_2\text{SO}_4 & x_2 \\ \hline \text{HCl} & x_3 \\ \hline \end{array}$$

$\text{BaSO}_4$ is sparingly soluble in water. If the conductivity of the saturated $\text{BaSO}_4$ solution is $x$ S cm$^{-1}$ then the solubility product of $\text{BaSO}_4$ can be given as
(Here $\Lambda_m = \Lambda_m^\circ$)

The correct statements among the following are.

A. Basic vanadium oxide is used in the manufacture of $H_2SO_4$.
B. The spin-only magnetic moment value of the transition metal halide employed in Ziegler-Natta polymerization is 2.84 BM.
C. The p-block metal compound employed in Ziegler-Natta polymerization has the metal in +3 oxidation state.
D. The number of electrons present in the outer most 'd' orbital of metal halide employed in Wacker process is 8.

Choose the correct answer from the options given below:

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

Match the LIST-I with LIST-II

Choose the correct answer from the options given below:

When 0.25 moles of a non-volatile, non-ionizable solute was dissolved in 1 mole of a solvent the vapor pressure of solution was $x \%$ of vapor pressure of pure solvent. What is $x \%$?

If shortest wavelength of hydrogen atom in Lyman series is $x$, then longest wavelength in Balmer series of $He^{+}$ is:

An oxide of iron contains $69.9\%$ iron, its empirical formula, is:
(Given : Molar mass of $Fe$ and $O$ are $56$ and $16\ g\ mol^{-1}$ respectively.)

Arrange the following isothermal processes in order of the magnitude of the work (p - V) involved between states 1 and 2.

A. Expansion in single stage $w_A$
B. Expansion in multi stages $w_B$
C. Compression in single stage $w_C$
D. Compression in multi stages $w_D$

Choose the correct option.

Match the LIST-I with LIST-II

Choose the correct answer from the options given below:

Match the column-I with column-II Column-I & & Column-II
(A) Aniline & & (P) Hinsberg reagent
(B) Benzaldehyde & & (Q) Tollen's reagent
(C) Phenol & & (R) Lucas reagent
(D) Isopropanol & & (S) Phthalein dye test
\endtabular \endcenter

If \(|x|\) represents the difference in maximum oxidation state possible for Mn in its oxide and in its fluoride. Among the following ions, which ions contain unpaired electrons equal to \(|x|\). (A) \(Zn^{2+}\) (B) \(Fe^{2+}\) (C) \(Co^{2+}\) (D) \(V^{2+}\) (E) \(Sc^{3+}\)

Consider the following complex compounds (A) \([Ni(NH_3)_6]^{2+}\) (B) \([NiCl_4]^{2-}\) (C) \([Ni(en)_3]^{2+}\) The number of unpaired electrons in A, B and C respectively and order of frequency of absorbed radiation among A, B and C is:

Which of the following ion forms a precipitate on addition of \(NH_4OH\) and \(H_2S\)?

Consider the following elements. Hf \([Z = 72]\) ; Yb \([Z = 70]\) ; Lu \([Z = 71]\) Gd \([Z = 64]\) ; Eu \([Z = 63]\) ; Tm \([Z = 69]\) Dy \([Z = 66]\) ; Er \([Z = 68]\) A : [Hf, Yb] B : [Gd, Eu] C : [Lu, Tm] D : [Er, Dy] The pair which contains same number of \(f\) electrons.

Element ‘M’ of group 13 has same electronegativity as Ge. Consider the statements (A) \(M^{3+}\) is good oxidizing agent (B) \(M^{3+}\) is good reducing agent (C) \(E^\circ_{M^{3+}/M} > 0\) (D) \(M^{3+}\) is more stable than \(M^{+}\) Which of the following is correct?

If first ionization enthalpy of Mg is \(738 \, \text{kJ/mol\) then second ionization enthalpy of Mg in kJ/mol will be :

Compare the C–O bond length in the following compounds (a) \(CH_3{-}CO{-}CH_3\) (b) Benzaldehyde type structure (c) \(CH_3{-}COO^{-}\) Compare C–O bond length.

Compound (X) has molar mass \(76\). \(2 \times 10^{-3}\) mole of X gives \(0.4813\,g\) \(BaSO_4\) as precipitate. What is the % of S in compound (X)? Mention answer in \(10^{-1}\) form.