List of top Questions asked in JEE Main- 2020

The correct match between Item - I and Item - II is :

Item - I	Item - II
(a) Natural rubber	(I) 1, 3-butadiene + styrene
(b) Neoprene	(II) 1, 3-butadiene + acrylonitrile
(c) Buna-N	(III) Chloroprene
(d) Buna-S	(IV) Isoprene

Which of the following compounds can be prepared in good yield by Gabriel phthalimide synthesis?

The increasing order of the boiling points of the major products A, B and C of the following reactions will be :

Match the following :

Test/Method	Reagent
(i) Lucas Test	(a) \(\mathrm{C_6H_5SO_2Cl}\)/ aq. KOH
(ii) Dumas method	(b) \(\mathrm{HNO_3}\)/ \(\mathrm{AgNO_3}\)
(iii) Kjeldahl's method	(c) \(\mathrm{CuO/CO_2}\)
(iv) Hinsberg test	(d) Conc. HCl and \(\mathrm{ZnCl_2}\)
	(e) \(\mathrm{H_2SO_4}\)

Mischmetal is an alloy consisting mainly of :

A set of solutions is prepared using 180 g of water as a solvent and 10 g of different nonvolatile solutes A, B and C. The relative lowering of vapour pressure in the presence of these solutes are in the order :
[Given, molar mass of A = 100 g mol\(^{-1}\); B = 200 g mol\(^{-1}\); C = 10,000 g mol\(^{-1}\)]

The average molar mass of chlorine is 35.5 g mol\(^{-1}\). The ratio of \(^{35}\mathrm{Cl}\) to \(^{37}\mathrm{Cl}\) in naturally occuring chlorine is close to :

For the given cell :
\(\mathrm{Cu(s)\,|\,Cu^{2+}(C_1\,M)\,||\,Cu^{2+}(C_2\,M)\,|\,Cu(s)}\)
change in Gibbs energy (\(\Delta G\)) is negative, if :

The correct match between Item-I (starting material) and Item-II (reagent) for the preparation of benzaldehyde is :

Item-I	Item-II
(I) Benzene	(P) HCl and \(\mathrm{SnCl_2}\), \(\mathrm{H_3O^+}\)
(II) Benzonitrile	(Q) \(\mathrm{H_2}\), Pd-\(\mathrm{BaSO_4}\), S and quinoline
(III) Benzoyl Chloride	(R) CO, HCl and \(\mathrm{AlCl_3}\)

Which one of the following statements is not true?

The value of \(K_C\) is 64 at 800 K for the reaction
\(\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}\)
The value of \(K_C\) for the following reaction is :
\(\mathrm{NH_3(g) \rightleftharpoons \frac{1}{2}N_2(g) + \frac{3}{2}H_2(g)}\)

For a \(\mathrm{d^4}\) metal ion in an octahedral field, the correct electronic configuration is :

The output characteristics of a transistor is shown in the figure.

When V_CE is 10 V and I_C = 4.0 mA, then value of \(\beta_{ac}\) is __________.

For a reaction,
\(4\mathrm{M(s)}+n\mathrm{O_2(g)}\rightarrow2\mathrm{M_2O_n(s)}\)
the free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which :

The centre of mass of solid hemisphere of radius 8 cm is x from the centre of the flat surface. Then value of x is __________.

In a series LR circuit, power of 400 W is dissipated from a source of 250 V, 50 Hz. The power factor of the circuit is 0.8. In order to bring the power factor to unity, a capacitor of value C is added in series to the L and R. Taking the value of C as \(\left(\frac{n}{3\pi}\right)\mu\)F, then value of n is __________.

For a plane electromagnetic wave, the magnetic field at a point x and time t is
\(\vec{B}(x,t)=\left[1.2\times10^{-7}\sin\left(0.5\times10^{3}x+1.5\times10^{11}t\right)\hat{k}\right]\) T
The instantaneous electric field \(\vec{E}\) corresponding to \(\vec{B}\) is :
(speed of light c = \(3\times10^{8}\) ms\(^{-1}\))

A student measuring the diameter of a pencil of circular cross-section with the help of a vernier scale records the following four readings 5.50 mm, 5.55 mm, 5.45 mm, 5.65 mm. The average of these four readings is 5.5375 mm and the standard deviation of the data is 0.07395 mm. The average diameter of the pencil should therefore be recorded as :

A Young's double-slit experiment is performed using monochromatic light of wavelength \(\lambda\). The intensity of light at a point on the screen, where the path difference is \(\lambda\), is K units. The intensity of light at a point where the path difference is \(\frac{\lambda}{6}\) is given by \(\frac{nK}{12}\), where n is an integer. The value of n is __________.

In the figure shown, the current in the 10 V battery is close to :

In a dilute gas at pressure \(P\) and temperature \(T\), the mean time between successive collisions of a molecule varies with \(T\) as :

A fluid is flowing through a horizontal pipe of varying cross-section, with speed \(v\ \mathrm{ms^{-1}}\) at a point where the pressure is \(P\) pascal. At another point where pressure is \(\dfrac{P}{2}\) Pascal its speed is \(V\ \mathrm{ms^{-1}}\). If the density of the fluid is \(\rho\ \mathrm{kg\,m^{-3}}\) and the flow is streamline, then \(V\) is equal to :

A particle moving in the xy plane experiences a velocity dependent force \(\vec F=k\left(v_y\hat i+v_x\hat j\right)\), where \(v_x\) and \(v_y\) are the x and y components of its velocity \(\vec v\). If \(\vec a\) is the acceleration of the particle, then which of the following statements is true for the particle?

Consider the force \(F\) on a charge \(q\) due to a uniformly charged spherical shell of radius \(R\) carrying charge \(Q\) distributed uniformly over it. Which one of the following statements is true for \(F\), if \(q\) is placed at distance \(r\) from the centre of the shell?

When a car is at rest, its driver sees rain drops falling on it vertically. When driving the car with speed \(v\), he sees that rain drops are coming at an angle \(60^\circ\) from the horizontal. On further increasing the speed of the car to \((1+\beta)v\), this angle changes to \(45^\circ\). The value of \(\beta\) is close to :