List of top Questions asked in JEE Main

Consider the following two first-order reactions: A $\to$ B (first reaction) C $\to$ D (second reaction) The rate constant for first reaction at 500 K is double of the same at 300 K. At 500 K, 50% of the reaction becomes complete in 2 hours. The activation energy of the second reaction is half of that of first reaction. If the rate constant at 500 K of the second reaction becomes double of the rate constant of first reaction at the same temperature; then rate constant for the second reaction at 300 K is ______ $\times 10^{-3}\,\text{hour}^{-1}$ (nearest integer).

For a strong electrolyte, molar conductivity increases slowly with dilution and can be represented by the equation:
Lambda_m = Lambda_m(0) − A × square root of c

Molar conductivity values of solutions of strong electrolyte AB at 18 degree Celsius are given below:

Concentration (mol L-1): 0.04 , 0.09 , 0.16 , 0.25
Molar conductivity (S cm2 mol-1): 96.1 , 95.7 , 95.3 , 94.9

The value of constant A based on the above data [in S cm2 mol-1 per (mol L-1)1/2] is:

Consider the following aqueous solutions. I. 2.2 g Glucose in 125 mL of solution. II. 1.9 g Calcium chloride in 250 mL of solution. III. 9.0 g Urea in 500 mL of solution. IV. 20.5 g Aluminium sulphate in 750 mL of solution. The correct increasing order of boiling point of these solutions will be: [Given: Molar mass in g mol$^{-1}$: H = 1, C = 12, N = 14, O = 16, Cl = 35.5, Ca = 40, Al = 27 and S = 32]

Identify the correct statements: The presence of –NO$_2$ group in benzene ring A. activates the ring towards electrophilic substitutions. B. deactivates the ring towards electrophilic substitutions. C. activates the ring towards nucleophilic substitutions. D. deactivates the ring towards nucleophilic substitutions. Choose the correct answer from the options given below:

Structures of four disaccharides are given below. Among the given disaccharides, the non-reducing sugar is:

Which of the following reaction is NOT correctly represented?

The correct increasing order of spin-only magnetic moment values of the complex ions:

[MnBr4]2− (A),
[Cu(H2O)6]2+ (B),
[Ni(CN)4]2− (C), and
[Ni(H2O)6]2+ (D)

is:

Consider the following statements about manganate and permanganate ions. Identify the correct statements. A. The geometry of both manganate and permanganate ions is tetrahedral. B. The oxidation states of Mn in manganate and permanganate are +7 and +6, respectively. C. Oxidation of Mn(II) salt by peroxodisulphate gives manganate ion as the final product. D. Manganate ion is paramagnetic and permanganate ion is diamagnetic. E. Acidified permanganate ion reduces oxalate, nitrite and iodide ions.

For the given reaction:
CaCO3 + 2HCl → CaCl2 + H2O + CO2

If 90 g CaCO3 is added to 300 mL of HCl which contains 38.55% HCl by mass and has density 1.13 g mL-1,
then which of the following option is correct?

Given molar mass of H, Cl, Ca and O are 1, 35.5, 40 and 16 g mol-1 respectively.

Match List - I with List - II according to shape. List - I A. XeO$_3$ B. XeF$_2$ C. XeO$_2$F$_2$ D. XeOF$_4$ List - II I. BrF$_5$ II. NH$_3$ III. [I$_3$]$^{-}$ IV. SF$_4$ Choose the correct answer from the options given below:

Given below are two statements: Statement I: The increasing order of boiling point of hydrogen halides is HCl<HBr<HI<HF. Statement II: The increasing order of melting point of hydrogen halides is HCl<HBr<HF<HI. In the light of the above statements, choose the correct answer from the options given below:

Observe the following equilibrium in a 1 L flask:
A(g) <=> B(g)

At temperature T (in K), the equilibrium concentrations of A and B are 0.5 M and 0.375 M respectively.
Then 0.1 moles of A is added into the flask and the system is heated to temperature T again to re-establish equilibrium.

The new equilibrium concentrations (in M) of A and B respectively are:

A student performed analysis of aliphatic organic compound 'X' which on analysis gave C = 61.01%, H = 15.25%, N = 23.74%. This compound, on treatment with HNO$_2$/H$_2$O produced another compound 'Y' which did not contain any nitrogen atom. However, the compound 'Y' upon controlled oxidation produced another compound 'Z' that responded to iodoform test. The structure of 'X' is:

The wavelength of photon 'A' is 400 nm. The frequency of photon 'B' is $10^{16}\,\text{s}^{-1}$. The wave number of photon 'C' is $10^{5}\,\text{cm}^{-1}$. The correct order of energy of these photons is:

Consider the following reactions:

The oxidation states of Cu in Z and Q, respectively are:

Total number of alkali insoluble solid sulphonamides obtained by reaction of given amines with Hinsberg's reagent is: Amines: Aniline, N-Methylaniline, Methanamine, N,N-Dimethylmethanamine, N-Methyl methanamine, Phenylmethanamine, N-propylaniline, N-phenylaniline, N,N-Dimethylaniline, Allyl amine, Isopropyl amine

The correct order of acidic strength of the major products formed in the given reactions is:

The cyclic cations having the same number of hyperconjugation are:

A student has been given 0.314 g of an organic compound and asked to estimate Sulphur. During the experiment, the student has obtained 0.4813 g of barium sulphate. The percentage of sulphur present in the compound is ________. (Given Molar mass in g mol$^{-1}$: S, 32; BaSO$_4$, 233)

The reactions which produce alcohol as the product are :

The plot of $\log_{10}K$ vs $\frac{1}{T}$ gives a straight line. The intercept and slope respectively are (where $K$ is equilibrium constant).

Consider the elements N, P, O, S, Cl and F. The number of valence electrons present in the elements with most and least metallic character from the above list is respectively.

A thermodynamic system is taken through the cyclic process $ABC$ as shown in the $P\!-\!V$ diagram. The total work done by the system during the cycle $ABC$ is _______ J.

Given: The area enclosed by the cycle in the $P\!-\!V$ diagram represents the work done.

An inductor stores $16\,\text{J}$ of magnetic field energy and dissipates $32\,\text{W}$ of thermal energy due to its resistance when an alternating current of $2\,\text{A}$ (rms) and frequency $50\,\text{Hz}$ flows through it. The ratio of inductive reactance to resistance is _______. $(\pi=3.14)$ Given: \[ U=16\,\text{J},\quad P=32\,\text{W},\quad I=2\,\text{A},\quad f=50\,\text{Hz} \]

A beam of light consisting of wavelengths $650\,\text{nm}$ and $550\,\text{nm}$ illuminates Young’s double slits with separation $d=2\,\text{mm}$ such that the interference fringes are formed on a screen placed at a distance $D=1.2\,\text{m}$ from the slits. The least distance from the central maximum, where the bright fringes due to both wavelengths coincide, is ________ $\times10^{-5}\,\text{m}$. Given: \[ \lambda_1=650\,\text{nm},\quad \lambda_2=550\,\text{nm},\quad d=2\times10^{-3}\,\text{m},\quad D=1.2\,\text{m} \]