List of top Questions asked in JEE Main- 2021

The major product of the following reaction is :
\(\mathrm{CH_3-CH(CH_3)-CH_2-CH_2-COCl}\)
(i) alcoholic \(\mathrm{NH_3}\)
(ii) \(\mathrm{NaOH,\ Br_2}\)
(iii) \(\mathrm{NaNO_2,\ HCl}\)
(iv) \(\mathrm{H_2O}\)
\(\longrightarrow\) Major Product
Match List - I with List - II.
List - IList - II
(a)\(R_H\) (Rydberg constant)(i)\(kg\,m^{-1}s^{-1}\)
(b)h (Planck's constant)(ii)\(kg\,m^2s^{-1}\)
(c)\(\mu_B\) (Magnetic field energy density)(iii)\(m^{-1}\)
(d)\(\eta\) (coefficient of viscocity)(iv)\(kg\,m^{-1}s^{-2}\)
Choose the most appropriate answer from the options given below :
The structures A and B formed in the following reaction are : [Ph = \(-\mathrm{C_6H_5}\)]
The major products A and B formed in the following reaction sequence are :
Identify products A and B.
Match List - I with List - II
List-IList-II
(a)Magnetic Induction(i)\(ML^2T^{-2}A^{-1}\)
(b)Magnetic Flux(ii)\(M^0L^{-1}A\)
(c)Magnetic Permeability(iii)\(MT^{-2}A^{-1}\)
(d)Magnetization(iv)\(MLT^{-2}A^{-2}\)
Choose the most appropriate answer from the options given below :
If \(\int \frac{\cos x - \sin x}{\sqrt{8 - \sin 2x}}\,dx = a\sin^{-1}\left(\frac{\sin x + \cos x}{b}\right) + c\), where c is a constant of integration, then the ordered pair (a, b) is equal to :
'A' and 'B' in the following reactions are :
The decomposition of formic acid on gold surface follows first order kinetics. If the rate constant at 300 K is 1.0 \(\times\) 10-3 s-1 and the activation energy Ea = 11.488 kJ mol-1, the rate constant at 200 K is ____________ \(\times\) 10-5 s-1. (Round off to the Nearest Integer). (Given : R = 8.314 J mol-1 K-1)
When light of wavelength 248 nm falls on a metal of threshold energy 3.0 eV, the de-Broglie wavelength of emitted electrons is _______ \(\mathring{\mathrm{A}}\). (Round off to the Nearest Integer).

[ Use : \(\sqrt{3}\) = 1.73, h = 6.63 \(\times\) 10-34 Js
me = 9.1 \(\times\) 10-31 kg; c = 3.0 \(\times\) 108 ms-1; 1eV = 1.6 \(\times\) 10-19 J]
A certain element crystallises in a bcc lattice of unit cell edge length 27 \(\mathring{\mathrm{A}}\). If the same element under the same conditions crystallises in the fcc lattice, the edge length of the unit cel in \(\mathring{\mathrm{A}}\) will be ____________. (Round off to the Nearest Integer).

[Assume each lattice point has a single atom]

[Assume \(\sqrt{3}\) = 1.73, \(\sqrt{2}\) = 1.41]
AB2 is 10% dissociated in water to A2+ and B-. The boiling point of a 10.0 molal aqueous solution of AB2 is __________\(^\circ\)C. (Round off to the Nearest Integer).

[Given : Molal elevation constant of water Kb = 0.5 K kg mol-1 boiling point of pure water = 100\(^\circ\)C]
\(2\mathrm{MnO_4^{-}} + b\,\mathrm{C_2O_4^{2-}} + c\,\mathrm{H^{+}} \rightarrow x\,\mathrm{Mn^{2+}} + y\,\mathrm{CO_2} + z\,\mathrm{H_2O}\)
If the above equation is balanced with integer coefficients, the value of c is ___________. (Round off to the Nearest Integer).
Two salts A\(_2\)X and MX have the same value of solubility product of 4.0 \(\times\) 10\(^{-12}\). The ratio of their molar solubilities i.e. \(\frac{S(A_2X)}{S(MX)}\) = __________. (Round off to the Nearest Integer)
The functions of antihistamine are :
For the reaction \(A(g) \rightleftharpoons B(g)\) at 495 K, \(\Delta_rG^\circ = -9.478\) kJ mol\(^{-1}\).
If we start the reaction in a closed container at 495 K with 22 millimoles of A, the amount of B in the equilibrium mixture is ____________ millimoles.
(Round off to the Nearest Integer). [R = 8.314 J mol\(^{-1}\) K\(^{-1}\); ln 10 = 2.303]
The equivalents of ethylene diamine required to replace the neutral ligands from the coordination sphere of the trans-complex of CoCl\(_3\) . 4NH\(_3\) is _________. (Round off to the Nearest Integer).
A 6.50 molal solution of KOH (aq.) has a density of 1.89 g cm-3. The molarity of the solution is ____________ mol dm-3. (Round off to the Nearest Integer).

[Atomic masses : K : 39.0 u; O : 16.0 u; H : 1.0 u]
The type of pollution that gets increased during the day time and in the presence of O\(_3\) is :
The process that involves the removal of sulphur from the ores is :
Given below are two statements :

Statement I : Both CaCl\(_2\) . 6H\(_2\)O and MgCl\(_2\) . 8H\(_2\)O undergo dehydration on heating.

Statement II : BeO is amphoteric whereas the oxides of other elements in the same group are acidic.

In the light of the above statements, choose the correct answer from the options given below :
Match List - I with List - II :
List - I
Industrial process		List - II
Application
(a)Haber's process(i)\(\mathrm{HNO_3}\) synthesis
(b)Ostwald's process(ii)Aluminium extraction
(c)Contact process(iii)\(\mathrm{NH_3}\) synthesis
(d)Hal-Heroult process(iv)\(\mathrm{H_2SO_4}\) synthesis

Choose the correct answer from the options given below :
Match List - I with List - II :
List - I
Name of oxo acid		List - II
Oxidation state of 'P'
(a)Hypophosphorous acid(i)+5
(b)Orthophosphoric acid(ii)+4
(c)Hypophosphoric acid(iii)+3
(d)Orthophosphorous acid(iv)+2
(v)+1

Choose the correct answer from the options given below :
Which of the following is Lindlar catalyst?

The products "A" and "B" formed in above reactions are :