List of top Questions asked in JEE Main- 2021

Match List - I with List - II. 

The incorrect statement among the following is :
What is the correct order of the following elements with respect to their density ?
The calculated magnetic moments (spin only value) for species $[FeCl_4]^{2-}$, $[Co(C_2O_4)_3]^{3-}$ and $MnO_4^{2-}$ respectively are :
Given below are two statements : Statement I : The value of the parameter “Biochemical Oxygen Demand (BOD)” is important for survival of aquatic life. Statement II : The optimum value of BOD is 6.5 ppm. In the light of the above statements, choose the most appropriate answer from the options given below :

The diazonium salt of which of the following compounds will form a coloured dye on reaction with β-Naphthol in NaOH ? 

Which one of the following compounds is non-aromatic ? 

The correct order of the following compounds showing increasing tendency towards nucleophilic substitution reaction is : (Note: The compounds are chloro benzene with different nitro positions: (i) Chlorobenzene, (ii) 4-nitrochlorobenzene, (iii) 2,4-dinitrochlorobenzene, (iv) 2,4,6-trinitrochlorobenzene)

Match List - I and List - II. List - I: (a) Valium, (b) Morphine, (c) Norethindrone, (d) Vitamin B12 List - II: (i) Antifertility drug, (ii) Pernicious anaemia, (iii) Analgesic, (iv) Tranquilizer
Match List - I and List - II. List - I : (a) R-COCl $\to$ R-CHO (b) R-CH2-COOH $\to$ R-CH-Cl-COOH (c) R-CONH2 $\to$ R-NH2 (d) R-COCH3 $\to$ R-CH2-CH3 List - II : (i) Br2/NaOH (ii) H2/Pd-BaSO4 (iii) Zn(Hg)/Conc. HCl (iv) Cl2/Red P, H2O
The formula of a gaseous hydrocarbon which requires 6 times of its own volume of O2 for complete oxidation and produces 4 times its own volume of CO2 is CxHy. The value of y is _________
The volume occupied by 4.75 g of acetylene gas at 50 °C and 740 mmHg pressure is _______ L. (Rounded off to the nearest integer) [Given \( R = 0.0826 \, \text{L atm K}^{-1} \text{ mol}^{-1} \)]
Assuming ideal behaviour, the magnitude of log K for the following reaction at 25 °C is \( x \times 10^{-1} \). The value of \( x \) is __________ . (Integer answer) \( 3\,\text{HC}\equiv\text{CH (g)} \rightleftharpoons \text{C}_6\text{H}_6 \text{ (l)} \) [Given : \( \Delta_f G^\circ (\text{HC}\equiv\text{CH}) = -2.04 \times 10^5 \,\text{J mol}^{-1} \); \( \Delta_f G^\circ (\text{C}_6\text{H}_6) = -1.24 \times 10^5 \,\text{J mol}^{-1} \); \( R = 8.314 \,\text{J K}^{-1} \text{ mol}^{-1} \)]
C6H6 freezes at 5.5°C. The temperature at which a solution of 10 g of C4H10 in 200 g of C6H6 freeze is ________ °C. (The molal freezing point depression constant of C6H6 is 5.12°C/m.)
The solubility product of PbI2 is \( 8.0 \times 10^{-9} \). The solubility of lead iodide in 0.1 molar solution of lead nitrate is \( x \times 10^{-6} \) mol/L. The value of \( x \) is __________. (Rounded off to the nearest integer) [Given \( \sqrt{2} = 1.41 \)]
The magnitude of the change in oxidising power of the MnO4− / Mn2+ couple is \( x \times 10^{-4} \) V, if the H+ concentration is decreased from 1 M to \( 10^{-4} \) M at 25 °C. (Assume concentration of MnO4− and Mn2+ to be same on change in H+ concentration). The value of \( x \) is __________ .
Sucrose hydrolyses in acid solution into glucose and fructose following first order rate law with a half-life of 3.33 h at 25 °C. After 9 h, the fraction of sucrose remaining is \( f \). The value of \( \log_{10}(1/f) \) is _______ × 10−2. (Rounded off to the nearest integer)
The total number of amines among the following which can be synthesized by Gabriel synthesis is _________. (A) ethylamine, (B) n-propylamine, (C) benzylamine, (D) aniline
1.86 g of aniline completely reacts to form acetanilide. 10% of the product is lost during purification. Amount of acetanilide obtained after purification (in g) is _________ × 10−2.
Let a, b ∈ R. If the mirror image of the point P(a, 6, 9) with respect to the line (x-3)/7 = (y-2)/5 = (z-1)/(-9) is (20, b, -a - 9), then |a + b| is equal to :
Let a, b, c be in arithmetic progression. Let the centroid of the triangle with vertices (a, c), (2, b) and (a, b) be (10/3, 7/3). If α, β are the roots of the equation ax² + bx + 1 = 0, then the value of α² + β² - αβ is :
If P is a point on the parabola y = x² + 4 which is closest to the straight line y = 4x - 1, then the co-ordinates of P are :
For which of the following curves, the line x + √3 y = 2√3 is the tangent at the point (3√3 / 2, 1/2) ?
The value of the integral, ∫ from 1 to 3 of [x² - 2x - 2] dx, where [x] denotes the greatest integer less than or equal to x, is :
The negation of the statement ~p ∧ (p ∨ q) is :