List of top Questions asked in JEE Main

Which one among the following resonating structures is not correct ?

An Organic compound 'A' $C_4H_8$ on treatment with $KMnO_4/H^+$ yields compound 'B' $C_3H_6O$. Compound 'A' also yields compound 'B' an ozonolysis. Compound 'A' is:

Consider the given reaction, the product 'X' is:

The given reaction can occur in the presence of:

(a) Bromine water
(b) $Br_2$ in $CS_2$, 273 K
(c) $Br_2/FeBr_3$
(d) $Br_2$ in $CHCl_3$, 273 K
Choose the correct answer from the options given below:

Which one of the products of the following reactions does not react with Hinsberg reagent to form sulphonamide?

Given below are two statements, one is labelled as Assertion (A) and other is labelled as Reason (R).
Assertion (A) : Gabriel phthalimide synthesis cannot be used to prepare aromatic primary amines.
Reason (R) : Aryl halides do not undergo nucleophilic substitution reaction.
In the light of the above statements, choose the correct answer from the options given below :

When 10 mL of an aqueous solution of $Fe^{2+}$ ions was titrated in the presence of dil $H_2SO_4$ using diphenylamine indicator, 15 mL of 0.02 M solution of $K_2Cr_2O_7$ was required to get the end point. The molarity of the solution containing $Fe^{2+}$ ions is $x \times 10^{-2}$ M. The value of $x$ is ________. (Nearest integer)

A home owner uses $4.00 \times 10^3 \text{ m}^3$ of methane ($CH_4$) gas, (assume $CH_4$ is an ideal gas) in a year to heat his home. Under the pressure of 1.0 atm and 300 K, mass of gas used is $x \times 10^5$ g. The value of $x$ is ________. (Nearest integer) (Given R = 0.083 L atm $K^{-1} mol^{-1}$)

A source of monochromatic radiation of wavelength 400 nm provides 1000 J of energy in 10 seconds. When this radiation falls on the surface of sodium, $x \times 10^{20}$ electrons are ejected per second. Assume that wavelength 400 nm is sufficient for ejection of electron from the surface of sodium metal. The value of $x$ is ________. (Nearest integer) ($h = 6.626 \times 10^{-34} \text{ Js}$)

The number of sigma bonds in $H_3C-CH=CH-C\equiv CH$ is ________.

At 298 K, the enthalpy of fusion of a solid (X) is 2.8 kJ $mol^{-1}$ and the enthalpy of vaporisation of the liquid (X) is 98.2 kJ $mol^{-1}$. The enthalpy of sublimation of the substance (X) in kJ $mol^{-1}$ is ________. (in nearest integer)

$CO_2$ gas is bubbled through water during a soft drink manufacturing process at 298 K. If $CO_2$ exerts a partial pressure of 0.835 bar then $x \text{ m mol}$ of $CO_2$ would dissolve in 0.9 L of water. The value of $x$ is ________. (Nearest integer) (Henry's law constant for $CO_2$ at 298 K is $1.67 \times 10^3$ bar)

For the reaction $A + B \rightleftharpoons 2C$ the value of equilibrium constant is 100 at 298 K. If the initial concentration of all the three species is 1 M each, then the equilibrium concentration of C is $x \times 10^{-1}$ M. The value of $x$ is ________. (Nearest integer)

Consider the cell at $25^{\circ}C$: $Zn | Zn^{2+} (aq, 1 \text{ M}) || Fe^{3+} (aq), Fe^{2+} (aq) | Pt(s)$. The fraction of total iron present as $Fe^{3+}$ ion at the cell potential of 1.500 V is $x \times 10^{-2}$. The value of $x$ is ________. (Nearest integer) (Given: $E^0_{Fe^{3+}/Fe^{2+}} = 0.77 \text{ V}$, $E^0_{Zn^{2+}/Zn} = -0.76 \text{ V}$)

Consider the complete combustion of butane, the amount of butane utilized to produce 72.0 g of water is ________ $\times 10^{-1}$ g. (in nearest integer)

Three moles of AgCl get precipitated when one mole of an octahedral co-ordination compound with empirical formula $CrCl_3 \cdot 3NH_3 \cdot 3H_2O$ reacts with excess of silver nitrate. The number of chloride ions satisfying the secondary valency of the metal ion is ________.

Let $y=y(x)$ be the solution of the differential equation $\frac{dy}{dx} = 1 + xe^{y-x}, -\sqrt{2}<x<\sqrt{2}, y(0) = 0$. Then, the minimum value of $y(x), x \in (-\sqrt{2}, \sqrt{2})$ is equal to :

Let $g: N \to N$ be defined as $g(3n+1) = 3n+2, g(3n+2) = 3n+3, g(3n+3) = 3n+1$, for all $n \ge 0$. Then which of the following statements is true ?

Let a parabola $P$ be such that its vertex and focus lie on the positive x-axis at a distance 2 and 4 units from the origin, respectively. If tangents are drawn from $O(0, 0)$ to the parabola $P$ which meet $P$ at $S$ and $R$, then the area (in sq. units) of $\Delta SOR$ is equal to :

If $b$ is very small as compared to the value of $a$, so that the cube and other higher powers of $\frac{b}{a}$ can be neglected in the identity $\frac{1}{a-b} + \frac{1}{a-2b} + \frac{1}{a-3b} + ....... + \frac{1}{a-nb} = \alpha n + \beta n^2 + \gamma n^3$, then the value of $\gamma$ is :

Let the vectors $(2 + a + b)\hat{i} + (a + 2b + c)\hat{j} - (b + c)\hat{k}$, $(1 + b)\hat{i} + 2\hat{j} - b\hat{k}$ and $(2 + b)\hat{i} + 2\hat{j} + (1 - b)\hat{k}$, $a, b, c \in \mathbb{R}$ be co-planar. Then which of the following is true ?

The number of real roots of the equation $e^{6x} - e^{4x} - 2e^{3x} - 12e^{2x} + e^x + 1 = 0$ is :

A spherical gas balloon of radius 16 meter subtends an angle $60^{\circ}$ at the eye of the observer A while the angle of elevation of its center from the eye of A is $75^{\circ}$. Then the height (in meter) of the top most point of the balloon from the level of the observer's eye is :