List of top Questions asked in JEE Main

On combustion 0.210 g of an organic compound containing C, H and O gave 0.127 g $ \text{H}_2\text{O} $ and 0.307 g $ \text{CO}_2 $. The percentages of hydrogen and oxygen in the given organic compound respectively are:

Match the LIST-I with LIST-II 

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In a first order decomposition reaction, the time taken for the decomposition of reactant to one fourth and one eighth of its initial concentration are $ t_1 $ and $ t_2 $ (s), respectively. The ratio $ t_1 / t_2 $ will be:

Match the LIST-I with LIST-II

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Which one of the following reactions will not lead to the desired ether formation in major proportion?
(iso-Bu = isobutyl, sec-Bu = sec-butyl, nPr = n-propyl, tBu = tert-butyl, Et = ethyl)

Correct statements for an element with atomic number 9 are 
A. There can be 5 electrons for which $ m_s = +\frac{1}{2} $ and 4 electrons for which $ m_s = -\frac{1}{2} $ 
B. There is only one electron in $ p_z $ orbital. 
C. The last electron goes to orbital with $ n = 2 $ and $ l = 1 $. 
D. The sum of angular nodes of all the atomic orbitals is 1. 
Choose the correct answer from the options given below:

The number of species from the following that are involved in $ sp^3d^2 $ hybridization is $ \text{[Co(NH}_3\text{)}_6\text{]}^{3+}, \text{SF}_6, \text{[CrF}_6\text{]}^{3-}, \text{[CoF}_6\text{]}^{3-}, \text{[Mn(CN)}_6\text{]}^{3-} $ and $ \text{[MnCl}_6\text{]}^{3-} $

When undergoes intramolecular aldol condensation, the major product formed is:


Choose the correct option for structures of A and B, respectively:

Choose the correct set of reagents for the following conversion:

Which of the following binary mixture does not show the behavior of minimum boiling azeotropes?
The atomic number of the element from the following with lowest $ 1^{\text{st}} $ ionization enthalpy is:

20 mL of sodium iodide solution gave 4.74 g silver iodide when treated with excess of silver nitrate solution. The molarity of the sodium iodide solution is _____ M. (Nearest Integer value) (Given : Na = 23, I = 127, Ag = 108, N = 14, O = 16 g mol$^{-1}$)

The equilibrium constant for decomposition of $ H_2O $ (g) $ H_2O(g) \rightleftharpoons H_2(g) + \frac{1}{2} O_2(g) \quad (\Delta G^\circ = 92.34 \, \text{kJ mol}^{-1}) $ is $ 8.0 \times 10^{-3} $ at 2300 K and total pressure at equilibrium is 1 bar. Under this condition, the degree of dissociation ($ \alpha $) of water is _____ $\times 10^{-2}$ (nearest integer value). [Assume $ \alpha $ is negligible with respect to 1]

Resonance in X$_2$Y can be represented as

The enthalpy of formation of X$_2$Y is 80 kJ mol$^{-1}$, and the magnitude of resonance energy of X$_2$Y is:

The energy of an electron in first Bohr orbit of H-atom is $-13.6$ eV. The magnitude of energy value of electron in the first excited state of Be$^{3+}$ is _____ eV (nearest integer value)

Consider the following half cell reaction $ \text{Cr}_2\text{O}_7^{2-} (\text{aq}) + 6\text{e}^- + 14\text{H}^+ (\text{aq}) \longrightarrow 2\text{Cr}^{3+} (\text{aq}) + 7\text{H}_2\text{O}(1) $ 
The reaction was conducted with the ratio of $\frac{[\text{Cr}^{3+}]^2}{[\text{Cr}_2\text{O}_7^{2-}]} = 10^{-6}$ 
The pH value at which the EMF of the half cell will become zero is ____ (nearest integer value) 
[Given : standard half cell reduction potential $\text{E}^\circ_{\text{Cr}_2\text{O}_7^{2-}, \text{H}^+/\text{Cr}^{3+}} = 1.33\text{V}, \quad \frac{2.303\text{RT}}{\text{F}} = 0.059\text{V}$

If the orthocentre of the triangle formed by the lines $ y = x + 1 $, $ y = 4x - 8 $, and $ y = mx + c $ is at $ (3, -1) $, then $ m - c $ is:
Let $ \vec{a} $ and $ \vec{b} $ be the vectors of the same magnitude such that $ \frac{| \vec{a} + \vec{b} | + | \vec{a} - \vec{b} |}{| \vec{a} + \vec{b} | - | \vec{a} - \vec{b} |} = \sqrt{2} + 1. \quad \text{Then } \frac{| \vec{a} + \vec{b} |^2}{| \vec{a} |^2} \text{ is:} $
Let $ A = \{(\alpha, \beta) \in \mathbb{R} \times \mathbb{R} : |\alpha - 1| \leq 4 \text{ and } |\beta - 5| \leq 6\} $ and $ B = \{(\alpha, \beta) \in \mathbb{R} \times \mathbb{R} : 16(\alpha - 2)^2 + 9(\beta - 6)^2 \leq 144\}. $ Then:
If the range of the function $ f(x) = \frac{5 - x}{x^2 - 3x + 2}, \quad x \neq 1, 2 $ is $ (-\infty, \alpha] \cup [\beta, \infty) $, then $ \alpha^2 + \beta^2 $ is equal to:
A bag contains 19 unbiased coins and one coin with heads on both sides. One coin is drawn at random and tossed, and heads turns up. If the probability that the drawn coin was unbiased is $ \frac{m}{n} $, where $ \gcd(m, n) = 1 $, then $ n^2 - m^2 $ is equal to:
Let a random variable X take values 0, 1, 2, 3 with $ P(X = 0) = P(X = 1) = p, \, P(X = 2) = P(X = 3), \, \text{and} \, F(X^2) = 2F(X). $ Then the value of $ 8p - 1 $ is:
If the area of the region $ \{(x, y) : 1 + x^2 \leq y \leq \min(x + 7, 11 - 3x)\} $ is $ A $, then $ 3A $ is equal to: