List of top Questions asked in JEE Main

A small block slides down from the top of hemisphere of radius R=3 m as shown in the figure. The height 'h' at which the block will lose contact with the surface of the sphere is ________ m. (Assume there is no friction between the block and the hemisphere) 

 

A swimmer wants to cross a river from point A to point B. Line AB makes an angle of 30$^\circ$ with the flow of river. Magnitude of velocity of the swimmer is same as that of the river. The angle $\theta$ with the line AB should be ________ $^\circ$, so that the swimmer reaches point B. 

 

A particle executes simple harmonic motion represented by displacement function as x(t) = A sin($\omega$t+$\phi$). If the position and velocity of the particle at t = 0 s are 2 cm and 2$\omega$ cm s$^{-1}$ respectively, then its amplitude is $x\sqrt{2}$ cm where the value of x is ________.
The difference in the number of waves when yellow light propagates through air and vacuum columns of the same thickness is one. The thickness of the air column is ________ mm.
[Refractive index of air = 1.0003, wavelength of yellow light in vacuum = 6000 Å]
Select the correct statements.
(A) Crystalline solids have long range order.
(B) Crystalline solids are isotropic.
(C) Amorphous solids are sometimes called pseudo solids.
(D) Amorphous solids soften over a range of temperatures.
(E) Amorphous solids have a definite heat of fusion.
Choose the most appropriate answer from the options given below :
If the Thompson model of the atom was correct, then the result of Rutherford's gold foil experiment would have been :
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : SO$_2$(g) is adsorbed to a larger extent than H$_2$(g) on activated charcoal.
Reason R : SO$_2$(g) has a higher critical temperature than H$_2$(g).
In the light of the above statements, choose the most appropriate answer from the options given below.
The CORRECT order of first ionisation enthalpy is :
The number of neutrons and electrons, respectively, present in the radioactive isotope of hydrogen is :
The addition of silica during the extraction of copper from its sulphide ore

Match List - I with List - II : 

Choose the correct answer from the options given below : 
 

Number of Cl=O bonds in chlorous acid, chloric acid and perchloric acid respectively are :
To an aqueous solution containing ions such as Al$^{3+}$, Zn$^{2+}$, Ca$^{2+}$, Fe$^{3+}$, Ni$^{2+}$, Ba$^{2+}$ and Cu$^{2+}$ was added conc. HCl, followed by H$_2$S.
The total number of cations precipitated during this reaction is/are :
Given below are two statements :
Statement I : [Mn(CN)$_6$]$^{3-}$, [Fe(CN)$_6$]$^{3-}$ and [Co(C$_2$O$_4$)$_3$]$^{3-}$ are d$^2$sp$^3$ hybridised.
Statement II : [MnCl$_6$]$^{3-}$ and [FeF$_6$]$^{3-}$ are paramagnetic and have 4 and 5 unpaired electrons, respectively.
Choose the correct option.

Match List - I with List - II : 

Choose the correct answer from the options given below : 
 

Which one of the following set of elements can be detected using sodium fusion extract ?
Given below are two statements :
Statement I : Hyperconjugation is a permanent effect.
Statement II : Hyperconjugation in ethyl cation \( (\mathrm{CH_3-CH_2^+}) \) involves the overlapping of \( \mathrm{C_{sp^2}-H_{1s}} \) bond with empty \( 2p \) orbital of the other carbon.
Choose the correct option :

Consider the above reaction, the major product "P" formed is : 

 

Consider the above reaction, and choose the correct statement : 

 

The correct sequence of correct reagents for the following transformation is : 

 

What is A in the following reaction ? 

2SO$_2$(g) + O$_2$(g) $\rightarrow$ 2SO$_3$(g)
The above reaction is carried out in a vessel starting with partial pressures P$_{SO_2}$ = 250 m bar, P$_{O_2}$ = 750 m bar and P$_{SO_3}$ = 0 bar. When the reaction is complete, the total pressure in the reaction vessel is ________ m bar. (Round off to the Nearest Integer).
The total number of electrons in all bonding molecular orbitals of O$_2^{2-}$ is ________.
(Round off to the Nearest Integer).
When 400 mL of 0.2 M H$_2$SO$_4$ solution is mixed with 600 mL of 0.1 M NaOH solution, the increase in temperature of the final solution is ________ $\times 10^{-2}$ K. (Round off to the Nearest Integer).
[Use : H$^+$(aq) + OH$^-$(aq) $\rightarrow$ H$_2$O(l) ; $\Delta_r H$ = -57.1 kJ mol$^{-1}$
Specific heat of H$_2$O = 4.18 J K$^{-1}$ g$^{-1}$
density of H$_2$O = 1.0 g cm$^{-3}$
Assume no change in volume of solution on mixing.]
In a solvent 50% of an acid HA dimerizes and the rest dissociates. The van't Hoff factor of the acid is ________ $\times 10^{-2}$. (Round off to the Nearest Integer).