List of top Questions asked in JEE Main- 2019

The correct statement (s) among I to III with respect to potassium ions that are abundant within the cell fluid is /are
I. They activate many enzymes
II. They participate in the oxidation of glucose to produce ATP
III. Along with sodium ions they are responsible for the transmission of nerve signals

Given
(i) C (graphite) + \(\mathrm{O_2(g)} \to \mathrm{CO_2(g)}\); \(\Delta_rH^{\ominus} = x\ \mathrm{kJ\ mol^{-1}}\)
(ii) C (graphite) + \(\frac{1}{2}\mathrm{O_2(g)} \to \mathrm{CO(g)}\); \(\Delta_rH^{\ominus} = y\ \mathrm{kJ\ mol^{-1}}\)
(iii) CO(g) + \(\frac{1}{2}\mathrm{O_2(g)} \to \mathrm{CO_2(g)}\); \(\Delta_rH^{\ominus} = z\ \mathrm{kJ\ mol^{-1}}\)
Based on the above thermochemical equations, find out which one of the following algebraic relationships is correct?

If the de Broglie wavelength of the electron in \(n^{th}\) Bohr orbit in a hydrogenic atom is equal to \(1.5\pi a_0\) (\(a_0\) is Bohr radius), then the value of \(n/z\) is -

The major product of the following reaction is –

(cyclopent-3-en-1-one treated with \(\mathrm{NaBH_4}\) in EtOH)

The aldehydes which will not form Grignard product with one equivalent Grignard reagents are -

(A) benzaldehyde; (B) 4-HO₂C-C₆H₄-CHO; (C) 4-H₃CO-C₆H₄-CHO; (D) 4-HOH₂C-C₆H₄-CHO

The major product in the following conversion is –

(4-methoxyphenyl)-CH=CH-CH₃ treated with HBr (excess), heat, gives ?

A paramagnetic material has \(10^{28}\) atoms/m\(^3\). Its magnetic susceptibility at temperature 350 K is \(2.8 \times 10^{-4}\). Its susceptibility at 300 K is :

To double the covering range of a TV transmission tower, its height should be multiplied by :

In a Frank-Hertz experiment, an electron of energy 5.6 eV passes through mercury vapour and emerges with an energy 0.7 eV. The minimum wavelength of photons emitted by mercury atoms is close to :

Formation of real image using a biconvex lens is shown below :

If the whole set up is immersed in water without disturbing the object and the screen positions, what will one observe on the screen ?

The element that does NOT show catenation is :

Two satellites, A and B, have masses m and 2m respectively. A is in a circular orbit of radius R, and B is in a circular orbit of radius 2R around the earth. The ratio of their kinetic energies, \(T_A/T_B\), is ;

When a certain photosensitive surface is illuminated with monochromatic light of frequency v, the stopping potential for the current is \(-V_0/2\). When the surface is illuminated by monochromatic light of frequency v/2, the stopping potential is \(-V_0\). The threshold frequency for photoelectric emission is :

The charge on a capacitor plate in a circuit, as a function of time, is shown in the figure :

What is the value of current at t = 4 s ?

A particle of mass 20 g is released with an initial velocity 5 m/s along the curve from the point A, as shown in the figure. The point A is at height h from point B. The particle slides along the frictionless surface. When the particle reaches point B, its angular momentum about O will be :
(Take g = 10 m/s²)

Let \(\ell\), r, C and V represent inductance, resistance, capacitance and voltage, respectively. The dimension of \(\frac{\ell}{rCV}\) in SI units will be :

The mean intensity of radiation on the surface of the Sun is about \(10^8\) W/m². The rms value of the corresponding magnetic field is closet to :

The equation of a tangent to the parabola, \(x^2=8y\), which makes an angle \(\theta\) with the positive directions of x-axis, is :

A parallel plate capacitor with plates of area 1 m² each, are at a separation of 0.1 m. If the electric field between the plates is 100 N/C, the magnitude of charge on each plate is :
(Take \(\varepsilon_0=8.85\times10^{-12}\ \frac{\mathrm{C^2}}{\mathrm{N\,m^2}}\))

Two particles A, B are moving on two concentric circles of radii \(R_1\) and \(R_2\) with equal angular speed \(\omega\). At t = 0, their positions and direction of motion are shown in the figure.

The relative velocity \(\vec V_A-\vec V_B\) at \(t=\frac{\pi}{2\omega}\) is given by :

A simple harmonic motion is represented by :
\(y=5(\sin3\pi t+\sqrt3\cos3\pi t)\) cm
The amplitude and time period of the motion are :

In the above circuit, \(C=\frac{\sqrt3}{2}\,\mu\mathrm{F}\), \(R_2=20\,\Omega\), \(L=\frac{\sqrt3}{10}\) H and \(R_1=10\,\Omega\). Current in L-\(R_1\) path is \(I_1\) and in C-\(R_2\) path it is \(I_2\). The voltage of A.C. source is given by, \(V=200\sqrt2\sin(100t)\) volts. The phase difference between \(I_1\) and \(I_2\) is :

If an angle between the line, \(\frac{x+1}{2}=\frac{y-2}{1}=\frac{z-3}{-2}\) and the plane, \(x-2y-kz=3\) is \(\cos^{-1}\left(\frac{2\sqrt{2}}{3}\right)\), then a value of k is :

Let S be the set of all real values of \(\lambda\) such that a plane passing through the points \((-\lambda^2,1,1)\), \((1,-\lambda^2,1)\) and \((1,1,-\lambda^2)\) also passes through the point \((-1,-1,1)\). Then S is equal to :

If the sum of the first 15 terms of the series \(\left(\frac{3}{4}\right)^3+\left(1\frac{1}{2}\right)^3+\left(2\frac{1}{4}\right)^3+3^3+\left(3\frac{3}{4}\right)^3+\ldots\) is equal to 225 k, then k is equal to :