List of top Questions asked in JEE Main

In polythionic acid, H\(_2\)S\(_x\)O\(_6\) (x = 3 to 5) the oxidation state(s) of sulphur is/are :
The gas 'A' is having very low reactivity reaches to stratosphere. It is non-toxic and non-flammable but dissociated by UV-radiations in stratosphere. The intermediates formed initially from the gas 'A' are:

In the following sequence of reactions, the final product D is : 

 

In the following sequence of reactions the P is: 

The structure of the starting compound P used in the reaction given below is: 

 

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Synthesis of ethyl phenyl ether may be achieved by Williamson synthesis.
Reason (R): Reaction of bromobenzene with sodium ethoxide yields ethyl phenyl ether.
In the light of the above statements, choose the most appropriate answer from the options given below :

The major product of the following reaction is: 

Which of the following is not a correct statement for primary aliphatic amines?

The correct statement about (A), (B), (C) and (D) is: 

Out of following isomeric forms of uracil, which one is present in RNA? 

Acidic ferric chloride solution on treatment with excess of potassium ferrocyanide gives a Prussian blue coloured colloidal species. It is:
The kinetic energy of an electron in the second Bohr orbit of a hydrogen atom is equal to \(\frac{h^2}{x m a_0^2}\). The value of \(10x\) is _________. (\(a_0\) is radius of Bohr's orbit)
(Nearest integer)
[ Given : \(\pi = 3.14\) ]
200 mL of 0.2 M HCl is mixed with 300 mL of 0.1 M NaOH. The molar heat of neutralization of this reaction is \(-57.1\) kJ. The increase in temperature in \(^\circ C\) of the system on mixing is \(x \times 10^{-2}\). The value of \(x\) is _________. (Nearest integer)
[ Given : Specific heat of water \(= 4.18 \, \text{J g}^{-1} \text{K}^{-1}\)
Density of water \(= 1.00 \, \text{g cm}^{-3}\) ]
(Assume no volume change on mixing)
1 kg of 0.75 molal aqueous solution of sucrose can be cooled up to \(-4^\circ C\) before freezing. The amount of ice (in g) that will be separated out is _________. (Nearest integer)
[ Given : \(K_f(H_2O) = 1.86 \, \text{K kg mol}^{-1}\) ]
The number of moles of \(NH_3\) that must be added to 2 L of 0.80 M \(AgNO_3\) in order to reduce the concentration of \(Ag^+\) ions to \(5.0 \times 10^{-8}\) M (\(K_{\text{formation}}\) for \([Ag(NH_3)_2]^+ = 1.0 \times 10^8\)) is _________. (Nearest integer)
[ Assume no volume change on adding \(NH_3\) ]
When 10 mL of an aqueous solution of \(KMnO_4\) was titrated in acidic medium, equal volume of 0.1 M of an aqueous solution of ferrous sulphate was required for complete discharge of colour. The strength of \(KMnO_4\) in grams per litre is _________ \(\times 10^{-2}\). (Nearest integer)
[ Atomic mass of \(K = 39, Mn = 55, O = 16\) ]
The reaction that occurs in a breath analyser, a device used to determine the alcohol level in a person's blood stream is:
\(2 K_2Cr_2O_7 + 8 H_2SO_4 + 3 C_2H_6O \to 2 Cr_2(SO_4)_3 + 3 C_2H_4O_2 + 2 K_2SO_4 + 11 H_2O\)
If the rate of appearance of \(Cr_2(SO_4)_3\) is \(2.67 \, \text{mol min}^{-1}\) at a particular time, the rate of disappearance of \(C_2H_6O\) at the same time is _________ \(\text{mol min}^{-1}\). (Nearest integer)
The number of \(f\) electrons in the ground state electronic configuration of Np (\(Z = 93\)) is _________. (Integer answer)
1 mol of an octahedral metal complex with formula $MCl_3 \cdot 2L$ on reaction with excess of $AgNO_3$ gives 1 mol of $AgCl$. The denticity of Ligand L is _________. (Integer answer)
In Carius method for estimation of halogens, 0.2 g of an organic compound gave 0.188 g of $AgBr$. The percentage of bromine in the compound is _________. (Nearest integer)
[Atomic mass : $Ag = 108, Br = 80$]
The number of moles of $CuO$, that will be utilized in Dumas method for estimating nitrogen in a sample of 57.5 g of N,N-dimethylaminopentane is $x \times 10^{-2}$. (Nearest integer)
If $S = \left\{z \in \mathbb{C} : \frac{z - i}{z + 2i} \in \mathbb{R}\right\}$, then :
If the matrix \( A = \begin{pmatrix} 0 & 2 \\ K & -1 \end{pmatrix} \) satisfies \( A(A^3 + 3I) = 2I \), then the value of \( K \) is :
If for $x, y \in \mathbb{R}, x>0, y = \log_{10} x + \log_{10} x^{1/3} + \log_{10} x^{1/9} + \dots$ upto $\infty$ terms and $\frac{2 + 4 + 6 + \dots + 2y}{3 + 6 + 9 + \dots + 3y} = \frac{4}{\log_{10} x}$, then the ordered pair $(x, y)$ is equal to :
If $\alpha, \beta$ are the distinct roots of $x^2 + bx + c = 0$, then $\lim_{x \to \beta} \frac{e^{2(x^2 + bx + c)} - 1 - 2(x^2 + bx + c)}{(x - \beta)^2}$ is equal to :