List of top Questions asked in JEE Main

The difference between spin only magnetic moment value of \([Co(H_2O)_6]Cl_2\) and \([Cr(H_2O)_6]Cl_3\) is ________ .
In the presence of sunlight, benzene reacts with CI2 to give product X. The number of hydrogens in X is _________.

An inductor of 0.5 mH, a capacitor of 200 μF and a resistor of 2 Ω are connected in series with a 220 V ac source. If the current is in phase with the emf, the frequency of ac source will be ______ × 102 Hz

Let O be the origin and A be the point \(z_1 = 1 + 2i\). If B is the point \(z_2, Re(z_2) < 0\), such that OAB is a right angled isosceles triangle with OB as hypotenuse, then which of the following is NOT true?
The distance of centre of mass from end \(A\) of a one dimensional rod (\(AB\)) having mass density \(ρ=ρ_0(1-\frac{x^2}{L^2})kg/m\) and length L. (in meter) is \(\frac{3L}{α} m\). The value of \(α\) is......... (where \(x\) is the distance form end \(A\))
The odd natural number a, such that the area of the region bounded by \(y = 1, y = 3, x = 0, x = y^a\) is \(\frac {364}{3}\), is equal to
Consider two G.Ps. \(2, 2^2, 2^3, ….\) and \(4, 4^2, 4^3, …\) of \(60\) and n terms respectively. If the geometric mean of all the \(60 + n\) terms is \((2)^{\frac {225}{8}}\) then \(\sum_{k=1}^{n}k(n−k)\) is equal to
The half life of a radioactive substance is 5 years. After x years, a given sample of the radioactive substance gets reduced to 6.25% of its initial value. The value of x is ______.
At a certain temperature, the degrees of freedom per molecule for gas is 8. The gas performs 150 J of work when it expands under constant pressure. The amount of heat absorbed by the gas will be ______ J.

Consider the species
\(CH_4,NH_{4}^+ and BH_{4}^−.\)
Choose the correct option with respect to these species.

4.0 moles of argon and 5.0 moles of PCl5 are introduced into an evacuated flask of 100 litre capacity at 610 K. The system is allowed to equilibrate. At equilibrium, the total pressure of mixture was found to be 6.0 atm. The Kp for the reaction is
 [Given : R = 0.082 L atm K–1 mol–1 ]
A 42.12% (w, v) solution of NaCl causes precipitation of a certain sol in 10 hours. The coagulating value of NaCl for the sol is
[Given : Molar mass : Na = 23.0 g mol–1; Cl = 35.5 g mol–1]

Match List-I with List-II
 

 List-I Ore List-II Composition
A.SideriteI.FeCO3
B.MalachiteII.CuCO3. Cu(OH)2
C.SphaleriteIII.ZnS
D.CalamineIV.ZnCO3


Choose the correct answer from the options given below:

Number of lone pair(s) of electrons on central atom and the shape of BrF3 molecule respectively, are
In Friedel-Crafts alkylation of aniline, one gets
Two isomers (A) and (B) with Molar mass 184 g/mol and elemental composition C, 52.2%; H, 4.9 % and Br 42.9% gave benzoic acid and p-bromobenzoic acid, respectively on oxidation with KMnO4. Isomer ‘A’ is optically active and gives a pale yellow precipitate when warmed with alcoholic AgNO3. Isomers ‘A’ and ‘B’ are, respectively.

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : Dacron is an example of polyester polymer.
Reason R : Dacron is made up of ethylene glycol and terephthalic acid monomers.
In the light of the above statements, choose the most appropriate answer from the options given below.

A white precipitate was formed when BaCl2 was added to water extract of an inorganic salt. Further, a gas ‘X’ with characteristic odour was released when the formed white precipitate was dissolved in dilute HCl. The anion present in the inorganic salt is
A box contains 0.90 g of liquid water in equilibrium with water vapour at 27°C. The equilibrium vapour pressure of water at 27°C is 32.0 Torr. When the volume of the box is increased, some of the liquid water evaporates to maintain the equilibrium pressure. 
If all the liquid water evaporates, then the volume of the box must be ______ litre. [nearest integer]
(Given : R = 0.082 L atm K–1 mol–1] (Ignore the volume of the liquid water and assume water vapours behave as an ideal gas.)
2.2 g of nitrous oxide (N2O) gas is cooled at a constant pressure of 1 atm from 310 K to 270 K causing the compression of the gas from 217.1 mL to 167.75 mL. The change in internal energy of the process, ΔU is ‘–x’ J. The value of ‘x’ is ____. [nearest integer]
(Given : atomic mass of N = 14 g mol–1 and of O = 16 g mol–1
Molar heat capacity of N2O is 100 J K–1 mol–1)
Elevation in boiling point for 1.5 molal solution of glucose in water is 4 K. The depression in freezing point for 4.5 molal solution of glucose in water is 4 K. The ratio of molal elevation constant to molal depression constant (Kb/Kf) is ___.
The cell potential for the given cell at 298 K \(\text{Pt} | \text{H}_2 \text{(g, 1 bar)} | \text{H}^+ \text{(aq)} || \text{Cu}^{2+} \text{(aq)} | \text{Cu(s)}\) is 0.31 V. The pH of the acidic solution is found to be 3, whereas the concentration of Cu2+ is 10–x M. The value of x is _____.
(Given : \(E^{Θ}_{Cu^{2+}/Cu}\) = 0.34 V and \(\frac{2.303RT}{F}\) = 0.06 V)
The equation k = (6.5 × 1012s–1)e–26000K/T is followed for the decomposition of compound A. The activation energy for the reaction is ______ kJ mol–1. [nearest integer]
(Given : R = 8.314 J K–1 mol–1]
Spin only magnetic moment of [MnBr6]4– is _____B.M. [round off to the closest integer]

For the reaction given below:
\(CoCl_3.xNH_3 + AgNO_3 (aq) →\)
If two equivalents of AgCl precipitate out, then the value of x will be____.