List of top Questions asked in JEE Main- 2020

An acidic solution of dichromate is electrolyzed for 8 minutes using 2A current. As per the following equation
\(\mathrm{Cr_2O_7^{2-} + 14H^+ + 6e^- \to 2Cr^{3+} + 7H_2O}\)
The amount of \(\mathrm{Cr^{3+}}\) obtained was 0.104 g. The efficiency of the process (in %) is (Take : F = 96000 C, At. mass of chromium = 52) ______.
If 250 cm3 of an aqueous solution containing 0.73 g of a protein A is isotonic with one litre of another aqueous solution containing 1.65 g of a protein B, at 298 K, the ratio of the molecular masses of A and B is ______ \(\times 10^{-2}\) (to the nearest integer).
A mixture of one mole each of H2 , He and O2 each are enclosed in a cylinder of volume V at temperature T. If the partial pressure of H2 is 2 atm, the total pressure of the gases in the cylinder is :
Match the following drugs with their therapeutic actions :
(i) Ranitidine(a) Antidepressant
(ii) Nardil (Phenelzine)(b) Antibiotic
(iii) Chloramphenicol(c) Antihistamine
(iv) Dimetane (Brompheniramine)(d) Antacid
(e) Analgesic
\(6.023 \times 10^{22}\) molecules are present in 10 g of a substance 'x'. The molarity of a solution containing 5 g of substance 'x' in 2 L solution is _____ \(\times 10^{-3}\)
The incorrect statement(s) among (a) – (d) regarding acid rain is (are) :

(a) It can corrode water pipes.
(b) It can damage structures made up of stone.
(c) It cannot cause respiratory ailments in animals.
(d) It is not harmful for trees
The incorrect statement is :
The increasing order of the reactivity of the following compound in nucleophilic addition reaction is :

Propanal, Benzaldehyde, Propanone, Butanone
Consider the hypothetical situation where the azimuthal quantum number, \(l\), takes values 0, 1, 2, ....., n + 1, where n is the principal quantum number. Then, the element with atomic number :
Complex A has a composition of \(\mathrm{H_{12}O_6Cl_3Cr}\). If the complex on treatment with conc.\(\mathrm{H_2SO_4}\) loses 13.5% of its original mass, the correct molecular formula of A is :
[Given: atomic mass of Cr = 52 amu and Cl = 35 amu]
The d-electron configuration of \(\mathrm{[Ru(en)_3]Cl_2}\) and \(\mathrm{[Fe(H_2O)_6]Cl_2}\), respectively are :
Among the statements (I - IV), the correct ones are:
(I) Be has smaller atomic radius compared to Mg.
(II) Be has higher ionization enthalpy than Al.
(III) Charge/radius ratio of Be is greater than that of Al.
(IV) Both Be and Al form mainly covalent compounds.
For the reaction
\(2A + 3B + \frac{3}{2}C \to 3P\), which statement is correct ?
When an object is kept at a distance of 30 cm from a concave mirror, the image is formed at a distance of 10 cm from the mirror. If the object is moved with a speed of 9 cms\(^{-1}\), the speed (in cms\(^{-1}\)) with which image moves at that instant is ____.
A block starts moving up an inclined plane of inclination \(30^\circ\) with an initial velocity of \(v_0\). It comes back to its initial position with velocity \(\dfrac{v_0}{2}\). The value of the coefficient of kinetic friction between the block and the inclined plane is close to \(\dfrac{I}{1000}\). The nearest integer to I is____.
The five successive ionization enthalpies of an element are 800, 2427, 3658, 25024 and 32824 kJ mol-1. The number of valence electrons in the element is :
If minimum possible work is done by a refrigerator in converting 100 grams of water at \(0^\circ\mathrm{C}\) to ice, how much heat (in calories) is released to the surroundings at temperature \(27^\circ\mathrm{C}\) (Latent heat of ice = 80 Cal/gram) to the nearest integer ?
A galvanometer coil has 500 turns and each turn has an average area of \(3\times10^{-4}\ \mathrm{m^2}\). If a torque of 1.5 Nm is required to keep this coil parallel to a magnetic field when a current of 0.5 A is flowing through it, the strength of the field (in T) is ______.
The strengths of 5.6 volume hydrogen peroxide (of density 1 g/mL) in terms of mass percentage and molarity (M), respectively, are: (Take molar mass of hydrogen peroxide as 34 g/mol)
A block of mass m attached to a massless spring is performing oscillatory motion of amplitude 'A' on a frictionless horizontal plane. If half of the mass of the block breaks off when it is passing through its equilibrium point, the amplitude of oscillation for the remaining system become fA. The value of f is :
A metallic sphere cools from 50\(^\circ\)C to 40\(^\circ\)C in 300 s. If atmospheric temperature around is 20\(^\circ\)C, then the sphere's temperature after the next 5 minutes will be close to :
The radius R of a nucleus of mass number A can be estimated by the formula
\(R = (1.3\times10^{-15})A^{1/3}\) m.
It follows that the mass density of a nucleus is of the order of :

\((M_{prot.} \cong M_{neut} \simeq 1.67\times10^{-27}\ \mathrm{kg})\)
Which of the following will NOT be observed when a multimeter (operating in resistance measuring mode) probes connected across a component, are just reversed?
The electric field of a plane electromagnetic wave propagating along the x direction in vacuum is \(\vec{E} = E_0\hat{j}\cos(\omega t - kx)\).
The magnetic field \(\vec{B}\), at the moment t = 0 is :
Two sources of light emit X-rays of wavelength 1 nm and visible light of wavelength 500 nm, respectively. Both the sources emit light of the same power 200 W. The ratio of the number density of photons of X-rays to the number density of photons of the visible light of the given wavelengths is :