List of top Questions asked in JEE Main

Choose the INCORRECT statement

Let $(h,k)$ lie on the circle $C:x^2+y^2=4$ and the point $(2h+1,\,3k+2)$ lie on an ellipse with eccentricity $e$. Then the value of $\dfrac{5}{e^2}$ is equal to

A student has planned to prepare acetanilide from aniline using acetic anhydride. The student has started from 9.3 g of aniline. However, the student has managed to obtain 11 g of dry acetanilide. The % yield of this reaction is

The heat of atomisation of methane and ethane are $ x $ kJ mol$^{-1}$ and $ y $ kJ mol$^{-1}$ respectively. The longest wavelength ($ \lambda $) of light capable of breaking the C–C bond can be expressed in SI unit as:

The velocity ($v$) – distance ($x$) graph is shown in the figure. Which graph represents acceleration ($a$) versus distance ($x$) variation of this system?

The number of possible tripeptides formed involving alanine (ala), glycine (gly) and valine (val), where no amino acid has been used more than once is

The binding energy for the following nuclear reactions are expressed in MeV.
\[ {}^{3}_{2}\text{He} + {}^{1}_{0}\text{n} \rightarrow {}^{4}_{2}\text{He} + 20 \text{ MeV} \] \[ {}^{4}_{2}\text{He} + {}^{1}_{0}\text{n} \rightarrow {}^{5}_{2}\text{He} - 0.9 \text{ MeV} \] If $ X_3, X_4, X_5 $ denote the stability of $ {}^{3}_{2}\text{He}, {}^{4}_{2}\text{He} $ and $ {}^{5}_{2}\text{He} $, respectively, then the correct order is:

In a meter bridge experiment to determine the value of unknown resistance, first the resistances $2\,\Omega$ and $3\,\Omega$ are connected in the left and right gaps of the bridge and the null point is obtained at a distance $l$ cm from the left end. Now, when an unknown resistance $x\,\Omega$ is connected in parallel to $3\,\Omega$, the null point is shifted by $10\,\text{cm}$ to the right. The value of $x$ is ________ $\Omega$.

In the group analysis of cations, Ba$^{2+}$ & Ca$^{2+}$ are precipitated respectively as

Given below are two statements regarding conformations of n-butane. Choose the correct option.

The wavelength of light absorbed for the following complexes are in the order
[Co(NH$_3$)$_6$]$^{3+}$ (I), [Co(H$_2$O)$_6$]$^{3+}$ (II), [Co(CN)$_6$]$^{3-}$ (III), [Co(NH$_3$)$_5$(H$_2$O)]$^{3+}$ (IV), [CoF$_6$]$^{3-}$ (V)

Given below are two statements:
Statement I: Cross aldol condensation between two different aldehydes will always produce four different products.
Statement II: When semicarbazide reacts with a mixture of benzaldehyde and acetophenone under optimum pH, it forms a condensation product with acetophenone only.

Five persons $P_1, P_2, P_3, P_4$ and $P_5$ recorded object distance ($u$) and image distance ($v$) using same convex lens having power $+5$ D as (25,96), (30,62), (35,37), (45,35) and (50,32) respectively. Identify correct statement.

Two liquids A and B form an ideal solution at temperature T K. At T K, the vapour pressures of pure A and pure B are 55 and 15 kPa respectively. What is the mole fraction of A in solution of A and B in equilibrium with a vapour in which the mole fraction of A is 0.8?

Let $S$ be a set of $5$ elements and $P(S)$ denote the power set of $S$. Let $E$ be the event of choosing an ordered pair $(A,B)$ from $P(S)\times P(S)$ such that $A\cap B=\varnothing$. If the probability of the event $E$ is $\dfrac{3^p}{2^q}$, where $p,q\in\mathbb{N}$, then $p+q$ is equal to

Consider two Group IV metal ions X$^{2+}$ and Y$^{2+}$. A solution containing 0.01 M X$^{2+}$ and 0.01 M Y$^{2+}$ is saturated with H$_2$S. The pH at which the metal sulphide YS will form as a precipitate is ___. (Nearest integer)
Given:
$K_{sp}(\mathrm{XS}) = 1 \times 10^{-22}$ at 25$^\circ$C
$K_{sp}(\mathrm{YS}) = 4 \times 10^{-16}$ at 25$^\circ$C
$[\mathrm{H_2S}] = 0.1$ M
$K_{a1} \times K_{a2} (\mathrm{H_2S}) = 1.0 \times 10^{-21}$
$\log 2 = 0.30,\ \log 3 = 0.48,\ \log 5 = 0.70$

X and Y are the number of electrons involved, respectively during the oxidation of I$^-$ to I$_2$ and S$^{2-}$ to S by acidified K$_2$Cr$_2$O$_7$. The value of X + Y is ___.

At $27^\circ\text{C}$, in presence of a catalyst, activation energy of a reaction is lowered by $10\,\text{kJ mol}^{-1}$. The logarithm of the ratio $\dfrac{k(\text{catalysed})}{k(\text{uncatalysed})}$ is ___.
(Consider that the frequency factor for both the reactions is same)

Given below are statements about some molecules/ions. Identify the CORRECT statements.
A. The dipole moment value of $\mathrm{NF_3}$ is higher than that of $\mathrm{NH_3}$.
B. The dipole moment value of $\mathrm{BeH_2}$ is zero.
C. The bond order of $\mathrm{O_2^{2-}}$ and $\mathrm{F_2}$ is same.
D. The formal charge on the central oxygen atom of ozone is $-1$.
E. In $\mathrm{NO_2}$, all the three atoms satisfy the octet rule, hence it is very stable.
Choose the correct answer from the options given below:

$A \rightarrow D$ is an endothermic reaction occurring in three elementary steps:
(i) $A \rightarrow B \quad \Delta H_i = +\text{ve}$
(ii) $B \rightarrow C \quad \Delta H_{ii} = -\text{ve}$
(iii) $C \rightarrow D \quad \Delta H_{iii} = -\text{ve}$
Which of the following graphs between potential energy (y-axis) versus reaction coordinate (x-axis) correctly represents the reaction profile of $A \rightarrow D$?

In Dumas method for estimation of nitrogen, 0.50 g of an organic compound gave 70 mL of nitrogen collected at 300 K and 715 mm pressure. The percentage of nitrogen in the organic compound is ____ %. (Aqueous tension at 300 K is 15 mm)

A voltage regulating circuit consisting of a Zener diode having breakdown voltage of $10\,\text{V}$ and maximum power dissipation of $0.4\,\text{W}$ is operated at $15\,\text{V}$. The approximate value of protective resistance in this circuit is ___ $\Omega$.

In the given figure, the blocks $A$, $B$ and $C$ weigh $4\,\text{kg}$, $6\,\text{kg}$ and $8\,\text{kg}$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is ___ N.
(Given: $g = 10\,\text{m s}^{-2}$)

Let a differentiable function $f$ satisfy \[ \int_0^{36} f\!\left(\frac{tx}{36}\right)dt=4\alpha f(x). \] If $y=f(x)$ is a standard parabola passing through the points $(2,1)$ and $(-4,\beta)$, then $\beta^2$ is equal to

Arrange the following alkenes in the decreasing order of stability:

Choose the correct answer from the options given below: