List of top Questions asked in JEE Main- 2020

If the constant term in the binomial expansion of \(\left(\sqrt{x}-\frac{k}{x^2}\right)^{10}\) is 405, then \(|k|\) equals :

For a suitably chosen real constant a, let a function, \(f:\mathbb{R}-\{-a\}\to\mathbb{R}\) be defined by \(f(x)=\frac{a-x}{a+x}\). Further suppose that for any real number \(x\ne -a\) and \(f(x)\ne -a\), \((f\circ f)(x)=x\). Then \(f\left(-\frac12\right)\) is equal to :

For all twice differentiable functions \(f:\mathbb{R}\to\mathbb{R}\), with \(f(0)=f(1)=f'(0)=0\)

Let L denote the line in the xy-plane with x and y intercepts as 3 and 1 respectively. Then the image of the point \((-1,-4)\) in this line is :

The area (in sq. units) of the region enclosed by the curves \(y=x^2-1\) and \(y=1-x^2\) is equal to :

The integral
\(\int_1^2 e^x \cdot x^x\,(2+\log_e x)\,dx\)
equals :

Potassium chlorate is prepared by the electrolysis of KCl in basic solution

\(6\mathrm{OH^-} + \mathrm{Cl^-} \to \mathrm{ClO_3^-} + 3\mathrm{H_2O} + 6e^-\)

If only 60% of the current is utilized in the reaction, the time (rounded to the nearest hour) required to produce 10 g of \(\mathrm{KClO_3}\) using a current of 2 A is ______.

(Given : F = 96,500 C \(\mathrm{mol^{-1}}\); molar mass of \(\mathrm{KClO_3}\) = 122 g \(\mathrm{mol^{-1}}\))

In an estimation of bromine by Carius method, 1.6 g of an organic compound gave 1.88 g of AgBr. The mass percentage of bromine in the compound is ______.
(Atomic mass, Ag = 108, Br = 80 g \(\mathrm{mol^{-1}}\))

The elevation of boiling point of 0.10 m aqueous \(\mathrm{CrCl_3 \cdot xNH_3}\) solution is two times that of 0.05 m aqueous \(\mathrm{CaCl_2}\) solution. The value of x is ______.

[Assume 100% ionisation of the complex and \(\mathrm{CaCl_2}\), coordination number of Cr as 6, and that all \(\mathrm{NH_3}\) molecules are present inside the coordination sphere]

A spherical balloon of radius 3 cm containing helium gas has a pressure of \(48 \times 10^{-3}\) bar. At the same temperature, the pressure, of a spherical balloon of radius 12 cm containing the same amount of gas will be ______ \(\times 10^{-6}\) bar.

The incorrect statement is :

Among the sulphates of alkaline earth metals, the solubilities of BeSO₄ and MgSO₄ in water, respectively, are :

The number of Cl = O bonds in perchloric acid is, "________".

Consider the Assertion and Reason given below.

Assertion (A) : Ethene polymerized in the presence of Ziegler Natta Catalyst at high temperature and pressure is used to make buckets and dustbins.

Reason (R) : High density polymers are closely packed and are chemically inert.

Choose the correct answer from the following:

The presence of soluble fluoride ion upto 1 ppm concentration in drinking water, is :

Arrange the following solutions in the decreasing order of pOH :

(A) 0.01 M HCl
(B) 0.01 M NaOH
(C) 0.01 M CH₃COONa
(D) 0.01 M NaCl

A solution of two components containing n₁ moles of the 1^st component and n₂ moles of the 2^nd component is prepared. M₁ and M₂ are the molecular weights of component 1 and 2 respectively. If d is the density of the solution in g mL^-1, C₂ is the molarity and x₂ is the mole fraction of the 2^nd component, then C₂ can be expressed as :

Which of the following compounds shows geometrical isomerism?

The species that has a spin-only magnetic moment of 5.9 BM, is :
(T_d = tetrahedral)

For the reaction

Fe₂N(s) + \(\frac{3}{2}\)H₂(g) \(\rightleftharpoons\) 2Fe(s) + NH₃(g)

The increasing order of pK_b values of the following compounds is :

(I) 4-methoxy-N,N-dimethylaniline, (II) N,N-dimethylaniline, (III) N-methylaniline with CN at the meta position, (IV) N-methylaniline with OH at the meta position.

Consider the following reactions

'A' is :

The lanthanoid that does NOT show +4 oxidation state is :

The set that contains atomic numbers of only transition elements, is :

The variation of equilibrium constant with temperature is given below :

Temperature	Equilibrium Constant
T1 = 25\(^\circ\)C	K1 = 10
T2 = 100\(^\circ\)C	K2 = 100

The values of \(\Delta H^\circ\), \(\Delta G^\circ\) at T₁ and \(\Delta G^\circ\) at T₂ (in kJ mol^-1) respectively, are close to :
[Use R = 8.314 J K^-1 mol^-1]