List of top Questions asked in JEE Main- 2021

Match List - I with List - II :
List - I (a) Mercury (b) Copper (c) Silicon (d) Nickel
List - II (i) Vapour phase refining (ii) Distillation Refining (iii) Electrolytic Refining (iv) Zone Refining Choose the most appropriate answer from the option given below :
In basic medium, H₂O₂ exhibits which of the following reactions ? (A) Mn²⁺ → Mn⁴⁺ (B) I₂ → I⁻ (C) PbS → PbSO₄ Choose the most appropriate answer from the options given below :
Match List - I with List - II : List - I (a) Be (b) Mg (c) Ca (d) Ra List - II (i) treatment of cancer (ii) extraction of metals (iii) incendiary bombs and signals (iv) windows of X-ray tubes (v) bearings for motor engines. Choose the most appropriate answer from the option given below :
The oxidation states of nitrogen in NO, NO₂, N₂O and NO₃⁻ are in the order of :
The oxide that shows magnetic property is :
The secondary valency and the number of hydrogen bonded water molecule(s) in CuSO₄·5H₂O, respectively, are :
Given below are two statements : Statement I : Non-biodegradable wastes are generated by the thermal power plants. Statement II : Bio-degradable detergents lead to eutrophication. In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : Statement I : C₂H₅OH and AgCN both can generate nucleophile. Statement II : KCN and AgCN both will generate nitrile nucleophile with all reaction conditions. Choose the most appropriate option :

In the following molecule,

Hybridisation of Carbon a, b and c respectively are :

Main Products formed during a reaction of 1-methoxy naphthalene with hydroiodic acid are :

In the reaction of hypobromite with amide, the carbonyl carbon is lost as :

Consider the above reaction, the product 'X' and 'Y' respectively are 

An organic compound "A" on treatment with benzene sulphonyl chloride gives compound B. B is soluble in dil. NaOH solution. Compound A is :

Consider the given reaction, percentage yield of : 

Match List - I with List - II :
List - I (a) Antifertility drug (b) Antibiotic (c) Tranquilizer (d) Artificial Sweetener
List - II (i) Meprobamate (ii) Alitame (iii) Norethindrone (iv) Salvarsan Choose the most appropriate match :
Deficiency of vitamin K causes :
10.0 mL of Na₂CO₃ solution is titrated against 0.2 M HCl solution. The following titre values were obtained in 5 readings: 4.8 mL, 4.9 mL, 5.0 mL, 5.0 mL and 5.0 mL. Based on these readings, and convention of titrimetric estimation the concentration of Na₂CO₃ solution is ________ mM. (Round off to the Nearest Integer).
The number of species below that have two lone pairs of electrons in their central atom is _________. (Round off to the Nearest Integer). SF₄, BF₄⁻, ClF₃, AsF₃, PCl₅, BrF₅, XeF₄, SF₆
The gas phase reaction 2A(g) ⇌ A₂(g) at 400 K has ΔG° = +25.2 kJ mol⁻¹. The equilibrium constant K_p for this reaction is _________ × 10^{-2}. (Round off to the Nearest Integer). [Use : R = 8.3 J mol⁻¹ K⁻¹, ln 10 = 2.3, log₁₀ 2 = 0.30, 1 atm = 1 bar, antilog (-0.3) = 0.501]
A solute A dimerizes in water. The boiling point of a 2 molal solution of A is 100.52°C. The percentage association of A is _________. (Round off to the Nearest Integer). [Use : K_b for water = 0.52 K kg mol⁻¹, Boiling point of water = 100°C]
The solubility of CdSO₄ in water is 8.0 × 10^{-4} mol L^{-1}. Its solubility in 0.01 M H₂SO₄ solution is ________ × 10^{-6} mol L^{-1}. (Round off to the Nearest Integer). (Assume that solubility is much less than 0.01 M)
The molar conductivities at infinite dilution of barium chloride, sulphuric acid and hydrochloric acid are 280, 860 and 426 S cm² mol⁻¹ respectively. The molar conductivity at infinite dilution of barium sulphate is ________ S cm² mol⁻¹. (Round off to the Nearest Integer).
A reaction has a half life of 1 min. The time required for 99.9% completion of the reaction is ________ min. (Round off to the Nearest Integer). [Use : ln 2 = 0.69; ln 10 = 2.3]
A xenon compound 'A' upon partial hydrolysis gives XeO₂F₂. The number of lone pair of electrons present in compound A is _________. (Round off to the Nearest Integer)

Consider the above reaction where 6.1 g of Benzoic acid is used to get 7.8 g of m-bromo benzoic acid. The percentage yield of the product is _________. (Round off to the Nearest Integer). [Given : Atomic masses : C : 12.0 u, H : 1.0 u, O : 16.0 u, Br : 80.0 u]