List of top Chemistry Questions asked in JEE Main

Grignard reagent RMgBr (P) reacts with water and forms a gas (Q). One gram of Q occupies 1.4 dm$^3$ at STP. (P) on reaction with dry ice in dry ether followed by H$_3$O$^+$ forms compound (Z). 0.1 mole of (Z) will weigh _________ g (Nearest integer).

The correct order of C, N, O and F in terms of second ionisation potential is

Pair of species among the following having same bond order as well as paramagnetic character will be:

Given below are two statements:
Statement I: The dipole moment of R–CN is greater than R–NC and R–NC can undergo hydrolysis under acidic medium to produce R–COOH.
Statement II: R–CN hydrolyses under acidic medium to produce a compound which on treatment with SOCl$_2$, followed by the addition of NH$_3$ gives another compound (X). This compound (X) on treatment with NaOCl/NaOH gives a product, that on treatment with CHCl$_3$/KOH/$\Delta$ produces R–NC.
In the light of the above statements, choose the correct answer from the options given below.

The unsaturated ether on acidic hydrolysis produces carbonyl compounds as shown below. Based on this, predict the solution/reagent that will help to distinguish "P" and "Q" obtained in the reaction.

Consider the following gaseous equilibrium in a closed container of volume $V$ at temperature $T$:
P$_2$(g) + Q$_2$(g) $\rightleftharpoons$ 2PQ(g)
Initially, 2 moles each of P$_2$(g), Q$_2$(g) and PQ(g) are present at equilibrium. One mole each of P$_2$ and Q$_2$ are added. The number of moles of P$_2$, Q$_2$ and PQ at the new equilibrium respectively are

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:

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

Choose the INCORRECT statement

``X'' is an oxoanion of the lightest element of group 17 (in the periodic table). The metal is in +6 oxidation state in ``X''. The color of the potassium salt of X is

At 298 K, the mole percentage of N$_2$(g) in air is 80%. Water is in equilibrium with air at a pressure of 10 atm. What is the mole fraction of N$_2$(g) in water at 298 K? ($K_H$ for N$_2$ = $6.5 \times 10^7$ mm Hg)

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

One mole of Cl$_2$(g) was passed into 2 L of cold 2 M KOH solution. After the reaction, the concentrations of Cl$^-$, ClO$^-$ and OH$^-$ are respectively (assume volume remains constant)

A chromium complex with formula CrCl$_3\cdot$6H$_2$O has a spin only magnetic moment value of 3.87 BM and its solution conductivity corresponds to 1:2 electrolyte. 2.75 g of the complex solution was initially passed through a cation exchanger. The solution obtained after the process was reacted with excess of AgNO$_3$. The amount of AgCl formed in the above process is _________ g (Nearest integer).
(Given: Molar mass in g mol$^{-1}$ Cr: 52; Cl: 35.5; Ag:108; O:16; H:1)

The half-life of $^{65}$Zn is 245 days. After $x$ days, 75% of the original activity remained. The value of $x$ in days is __________ (Nearest integer).}
(Given: $\log 3 = 0.4771$ and $\log 2 = 0.3010$)

Find out the statements which are not true.
A. Resonating structures with more covalent bonds and less charge separation are more stable.
B. In electromeric effect, an unsaturated system shows +E effect with nucleophile and –E effect with electrophile.
C. Inductive effect is responsible for high melting point, boiling point and dipole moment of polar compounds.
D. The greater the number of alkyl groups attached to the doubly bonded carbon atoms, higher is the heat of hydrogenation.
E. Stability of carbanion increases with increase in s-character of the carbon carrying negative charge.

Molar conductivity of a weak acid HQ of concentration 0.18 M was found to be \( \dfrac{1}{30} \) of the molar conductivity of another weak acid HZ with concentration 0.02 M. If \( \alpha_Q \) happened to be equal to \( \alpha_Z \), then the difference of the pK_a values of the two weak acids (pK_a(HQ) − pK_a(HZ)) is ________ (Nearest integer).
(Given: degree of dissociation \( \alpha \ll 1 \) for both weak acids, \( \lambda^\circ \): limiting molar conductivity of ions)

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)

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?

Consider three metal chlorides $x$, $y$ and $z$, where $x$ is water soluble at room temperature, $y$ is sparingly soluble in water at room temperature and $z$ is soluble in hot water. $x$, $y$ and $z$ are respectively ___.

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: