List of top Questions asked in JEE Main

[P] on treatment with \(\mathrm{Br_2/FeBr_3}\) in \(\mathrm{CCl_4}\) produced a single isomer \(\mathrm{C_8H_7O_2Br}\) while heating [P] with sodalime gave toluene. The compound [P] is :

The decreasing order of reactivity of the following organic molecules towards \(\mathrm{AgNO_3}\) solution is :

A perfectly diamagnetic sphere has a small spherical cavity at its centre, which is filled with a paramagnetic substance. The whole system is placed in a uniform magnetic field \(\vec{B}\). Then the field inside the paramagnetic substance is :

An organic compound (A) (molecular formula \(\mathrm{C_6H_{12}O_2}\)) was hydrolysed with dil. \(\mathrm{H_2SO_4}\) to give a carboxylic acid (B) and an alcohol (C). 'C' gives white turbidity immediately when treated with anhydrous \(\mathrm{ZnCl_2}\) and conc. HCl. The organic compound (A) is :

The intermolecular potential energy for the molecules A, B, C and D given below suggests that :

When neopentyl alcohol is heated with an acid, it slowly converted into an 85 : 15 mixture of alkenes A and B, respectively. What are these alkenes ?

The IUPAC name of the following compound is :

The number of chiral centres present in [B] is ________.

(Reaction scheme as drawn: 3-methylcyclohexyl-CH(CH₃)-C\(\equiv\)N; (i) C₂H₅MgBr, (ii) H₃O⁺ gives [A]; the same nitrile with (i) CH₃MgBr, (ii) H₂O gives [B].)

A uniform rod of length '\(l\)' is pivoted at one of its ends on a vertical shaft of negligible radius. When the shaft rotates at angular speed \(\omega\) the rod makes an angle \(\theta\) with it (see figure). To find \(\theta\) equate the rate of change of angular momentum (direction going into the paper)
\(\dfrac{ml^2}{12}\omega^2\sin\theta\cos\theta\)
about the centre of mass (CM) to the torque provided by the horizontal and vertical forces \(F_H\) and \(F_V\) about the CM. The value of \(\theta\) is then such that :

An massless equilateral triangle EFG of side 'a' (As shown in figure) has three particles of mass m situated at its vertices. The moment of inertia of the system about the line EX perpendicular to EG in the plane of EFG is \(\dfrac{N}{20}ma^2\) where N is an integer. The value of N is _____.

Consider the following molecules and statements related to them :

(a) (B) is more likely to be crystalline than (A)
(b) (B) has higher boiling point than (A)
(c) (B) dissolves more readily than (A) in water
Identify the correct option from below :

The major product in the following reaction is :

The decreasing order of reactivity of the following compounds towards nucleophilic substitution (S_N2) is :

Three isomers A, B and C (mol. formula \(\mathrm{C_8H_{11}N}\)) give the following results :

R has lower boiling point than S
A, B and C, respectively are :

Consider the following reaction :

The product 'P' gives positive ceric ammonium nitrate test. This is because of the presence of which of these -OH group(s)?

100 mL of 0.1 M HCl is taken in a beaker and to it 100 mL of 0.1 M NaOH is added in steps of 2 mL and the pH is continuously measured. Which of the following graphs correctly depicts the change in pH?

The compound A in the following reaction is :

An ionic micelle is formed on the addition of :

A block of mass \(m = 1\) kg slides with velocity \(v = 6\) m/s on a frictionless horizontal surface and collides with a uniform vertical rod and sticks to it as shown. The rod is pivoted about O and swings as a result of the collision making angle \(\theta\) before momentarily coming to rest. If the rod has mass \(M = 2\) kg, and length \(l = 1\) m, the value of \(\theta\) is approximately :
(take \(g = 10\) m/s\(^2\))

Consider a gas of triatomic molecules. The molecules are assumed to be triangular and made of massless rigid rods whose vertices are occupied by atoms. The internal energy of a mole of the gas at temperature T is :

An elliptical loop having resistance R, of semi major axis a, and semi minor axis b is placed in magnetic field as shown in the figure. If the loop is rotated about the x-axis with angular frequency \(\omega\), the average power loss in the loop due to Joule heating is :

In the circuit shown in the figure, the total charge is \(750\ \mu\)C and the voltage across capacitor \(C_2\) is 20 V. Then the charge on capacitor \(C_2\) is :

The number of

groups present in a tripeptide Asp–Glu–Lys is ____.

An observer can see through a small hole on the side of a jar (radius 15 cm) at a point at height of 15 cm from the bottom (see figure). The hole is at a height of 45 cm. When the jar is filled with a liquid up to a height of 30 cm the same observer can see the edge at the bottom of the jar. If the refractive index of the liquid is N/100, where N is an integer, the value of N is ________.

The mechanism of \(\mathrm{S_N1}\) reaction is given as :

A student writes general characteristics based on the given mechanism as :
(a) The reaction is favoured by weak nucleophiles.
(b) \(\mathrm{R^+}\) would be easily formed if the substituents are bulky.
(c) The reaction is accompanied by racemization.
(d) The reaction is favoured by non-polar solvents.