List of top Chemistry Questions asked in JEE Main

Time required for 99.9% completion of a first order reaction is _____ time the time required for completion of 90% reaction.(nearest integer).
The difference in the 'spin-only' magnetic moment values of \( \text{KMnO}_4 \) and the manganese product formed during titration of \( \text{KMnO}_4 \) against oxalic acid in acidic medium is ______ BM (nearest integer).
Consider the dissociation of the weak acid HX as given below:
\[\text{HX(aq)} \rightleftharpoons \text{H}^+(\text{aq}) + \text{X}^-(\text{aq}), \, K_a = 1.2 \times 10^{-5}\]
\([K_a: \text{dissociation constant}]\)
The osmotic pressure of \(0.03 \, \text{M}\) aqueous solution of HX at 300 K is ______ \( \times 10^{-2} \, \text{bar} \) (nearest integer).
Given: \(R = 0.083 \, \text{L bar mol}^{-1} \text{K}^{-1}\)
A conductivity cell with two electrodes (dark side) are half filled with infinitely dilute aqueous solution of a weak electrolyte. If volume is doubled by adding more water at constant temperature, the molar conductivity of the cell will -
Match List-I with the List-II
List-I
(Compound)		List-II
(Uses)
(A) Iodoform(I) Fire extinguisher
(B) Carbon
tetrachloride		(II) Insecticide
(C) CFC(III) Antiseptic
(D) DDT(IV) Refrigerants
Choose the correct answer from the options given below:

At \(-20^\circ \text{C}\) and 1 atm pressure, a cylinder is filled with an equal number of \(H_2\), \(I_2\), and \(HI\) molecules for the reaction: 
\[H_2(g) + I_2(g) \rightleftharpoons 2HI(g)\] The \(K_P\) for the process is \(x \times 10^{-1}\). 
(x = ___________)
Given: \(R = 0.082 \, \text{L atm K}^{-1} \text{mol}^{-1}\)

Which among the following aldehydes is most reactive towards nucleophilic addition reactions?
The density of 'x' M solution ('x' molar) of NaOH is \(1.12 \, \text{g/mL}\). While in molality, the concentration of the solution is \(3 \, \text{m}\) (3 molal). Then x is:
Given: Molar mass of NaOH is \(40 \, \text{g/mol}\)
The number of element from the following that do not belong to lanthanoids is :
Eu, Cm, Er, Tb, Yb and Lu
The electron affinity values are negative for:
A. Be → Be−
B. N → N−
C. O → O2−
D. Na → Na−
E. Al → Al−
Choose the most appropriate answer from the options given below:
Match List-I with the List-II
List-I
(Precipitating reagent and
conditions)		List-II
(Cation)
(A) \(NH_4Cl + NH_4OH\)(I) Mn2+
(B) \(NH_4OH + Na_2CO_3\)(II) Pb2+
(C) \(NH_4OH + NH_4Cl + H_2S gas\)(III) Al3+
(D) dilute HCl(IV) Sr2+
Choose the correct answer from the options given below:
Consider the following complexes:
\([CoCl(NH_3)_5]^{2+}\) (A)
\([Co(CN)_6]^{3-}\) (B)
\([Co(NH_3)_5(H_2O)]^{3+}\) (C)
\([Cu(H_2O)_4]^{2+}\) (D)
The correct order of A, B, C, and D in terms of wavenumber of light absorbed is:
Which of the following material is not a semiconductor.
In Reimer - Tiemann reaction, phenol is converted into salicylaldehyde through an intermediate. The structure of intermediate is ______.
Which of the following statements are correct ?
A. Glycerol is purified by vacuum distillation because it decomposes at its normal boiling point
B. Aniline can be purified by steam distillation as aniline is miscible in water.
C. Ethanol can be separated from ethanol water mixture by azeotropic distillation because it forms azeotrope.
D. An organic compound is pure, if mixed M.P. is remained same.
Choose the most appropriate answer from the options given below :
Given below are two statements :
Statement I : Gallium is used in the manufacturing of thermometers.
Statement II : A thermometer containing gallium is useful for measuring the freezing point (256 K) of brine solution.
In the light of the above statement, choose the correct answer from the options given below :
Match List-I with the List-II
List-I
(Hybridization)		List-II
(Orientation in
Space)
(A) sp3(I) Trigonal
bipyramidal
(B) dsp2(II) Octahedral
(C) sp3d(III) Tetrahedral
(D) sp3d2(IV) Square planar
Choose the correct answer from the options given below:
DNA molecule contains 4 bases whoes structure are shown below. One of the structure is not correct, identify the incorrect base structure.
Which of the following is metamer of the given compound (X) ?
Given below are two statements:
Statement I : Picric acid is 2, 4, 6-trinitrotoluene.
Statement II : Phenol-2, 4-disulphuric acid is treated with conc. HNO3 to get picric acid.
In the light of the above statement, choose the most appropriate answer from the options given below:
Match List-I with the List-II
List-I
(Molecule / Species)		List-II
(Property / Shape)
(A) \(SO_2Cl_2\)(I) Paramagnetic
(B) NO(II) Diamagnetic
(C) \(NO^{-}_{2}\)(III) Tetrahedral
(D) \(I^{-}_{3}\)(IV) Linear
Choose the correct answer from the options given below:
Functional group present in sulphonic acid is :
Number of colourless lanthanoid ions among the following is ____.
\[ \text{Eu}^{3+}, \, \text{Lu}^{3+}, \, \text{Nd}^{3+}, \, \text{La}^{3+}, \, \text{Sm}^{3+} \]
Total number of essential amino acid among the given list of amino acids is _______.
Arginine, Phenylalanine, Aspartic acid, Cysteine, Histidine, Valine, Proline
The total number of species from the following in which one unpaired electron is present, is ____.
\[ \text{N}_2, \text{O}_2, \text{C}_2^{-}, \text{O}_2^{-}, \text{H}_2^{+}, \text{CN}^{-}, \text{He}_2^{+} \]