List of top Questions asked in JEE Main

A radioactive isotope having a half - life period of 3 days was received after 12 days. If 3 g of the isotope is left in the container, what would be the initial mass of the isotope ?
The Gibbs energy for the decomposition of \(\mathrm{Al_2O_3}\) at 500 C is as follows :
\(\frac{2}{3}\mathrm{Al_2O_3} \rightarrow \frac{4}{3}\mathrm{Al} + \mathrm{O_2}\), \(\Delta_r G = +940\ \mathrm{kJ\ mol^{-1}}\) The potential difference needed for the electrolytic reduction of aluminium oxide at \(500^\circ\mathrm{C}\) should be at least :
Which one of the following arrangements represents the correct order of the proton affinity of the given species :
In which of the following octahedral complex species the magnitude of \(\Delta_o\) will be maximum?

Given
In the above compounds correct order of reactivity in electrophilic substitution reactions will be:
The ratio \(\frac{K_p}{K_c}\) for the reaction \(\mathrm{CO}(g) + \frac{1}{2}\mathrm{O_2}(g) \rightleftharpoons \mathrm{CO_2}(g)\) is:
What would be the pH of a solution obtained by mixing 5 g of acetic acid and 7.5 g of sodium acetate and making the volume equal to 500 mL ? (\(\mathrm{K_a} = 1.75 \times 10^{-5}\), \(\mathrm{pK_a} = 4.76\))
Given that: (i) \(\Delta_f H^\circ\) of \(\mathrm{N_2O}\) is 82 kJ \(\mathrm{mol^{-1}}\) (ii) Bond energies of \(\mathrm{N\equiv N, N=N, O=O}\) and \(\mathrm{N=O}\) are 946, 418, 498 and 607 kJ \(\mathrm{mol^{-1}}\) respectively, The resonance energy of \(\mathrm{N_2O}\) is :
The structure of which of the following chloro species can be explained on the basis of \(dsp^2\) hybridization?
The catenation tendency of C, Si and Ge is in the order Ge \(\lt\) Si \(\lt\) C. The bond energies (in kJ \(\mathrm{mol^{-1}}\) ) of C \(-\) C, Si \(-\) Si and Ge \(-\) Ge bonds are respectively ;
The internuclear distances in O \(-\) O bonds for \(\mathrm{O_2^+, O_2, O_2^-}\) and \(\mathrm{O_2^{2-}}\) respectively are :
Which one of the following cannot function as an oxidising agent?
In which of the following sets, all the given species are isostructural ?
In an experiment on photoelectric effect, a student plots stopping potential \(V_0\) against reciprocal of the wavelength \(\lambda\) of the incident light for two different metals A and B. These are shown in the figure.

Looking at the graphs, you can most appropriately say that:
A copper ball of radius 1 cm and work function 4.47 eV is irradiated with ultraviolet radiation of wavelength 2500 \(\mathrm{\AA}\). The effect of irradiation results in the emission of electrons from the ball. Further the ball will acquire charge and due to this there will be a finite value of the potential on the ball. The charge acquired by the ball is :
Which of the following circuits correctly represents the following truth table ?
ABC
000
010
101
110
Which of the following modulated signal has the best noise-tolerance ?
This question has Statement-1 and Statement-2. Of the four choices given after the Statements, choose the one that best describes the two Statements.
Statement-1 : Out of radio waves and microwaves, the radio waves undergo more diffraction.
Statement-2 : Radio waves have greater frequency compared to microwaves.
A thin glass plate of thickness \(\frac{2500}{3}\lambda\) (\(\lambda\) is wavelength of light used) and refractive index \(\mu = 1.5\) is inserted between one of the slits and the screen in Young's double slit experiment. At a point on the screen equidistant from the slits, the ratio of the intensities before and after the introduction of the glass plate is :
The source that illuminates the double − slit in 'double - slit interference experiment' emits two distinct monochromatic waves of wavelength 500 nm and 600 nm, each of them producing its own pattern on the screen. At the central point of the pattern when path difference is zero, maxima of both the patterns coincide and the resulting interference pattern is most distinct at the region of zero path difference. But as one moves out of this central region, the two fringe systems are gradually out of step such that maximum due to one wavelength coincides with the minimum due to the other and the combined fringe system becomes completely indistinct. This may happen when path difference in nm is:
One of the two small circular coils, (none of them having any self - inductance) is suspended with a V-shaped copper wire, with plane horizontal. The other coil is placed just below the first one with plane horizontal. Both the coils are connected in series with a dc supply. The coils are found to attract each other with a force. Which one of the following statements is incorrect?
When resonance is produced in a series LCR circuit, then which of the following is not correct?
A series LR circuit is connected to an ac source of frequency \(\omega\) and the inductive reactance is equal to 2R. A capacitance of capacitive reactance equal to R is added in series with L and R. The ratio of the new power factor to the old one is :
A metal sample carrying a current along X− axis with density \(J_x\) is subjected to a magnetic field \(B_z\) (along z− axis). The electric field \(E_y\) developed along Y-axis is directly proportional to \(J_x\) as well as \(B_z\). The constant of proportionality has SI unit.
The earth's magnetic field lines resemble that of a dipole at the centre of the earth. If the magnetic moment of this dipole is close to \(8\times 10^{22}\ \mathrm{Am^2}\), the value of earth's magnetic field near the equator is close to (radius of the earth = \(6.4\times 10^{6}\) m)