List of top Chemistry Questions

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).

0.25 g of an organic compound “A” containing carbon, hydrogen and oxygen was analysed using combustion method. The increase in mass of CaCl$_2$ tube and potash tube at the end of the experiment was found to be 0.15 g and 0.1837 g respectively. The percentage of oxygen in compound A is ________ % (Nearest integer).

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)

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 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 $\log 2 = 0.3010$)

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

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.

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.

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

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:

From the following, the least stable structure is:
(Assume standard resonance structures)

80 mL of a hydrocarbon on mixing with 264 mL of oxygen in a closed U-tube undergoes complete combustion. The residual gases after cooling to 273 K occupy 224 mL. When the system is treated with KOH solution, the volume decreases to 64 mL. The formula of the hydrocarbon is:

Which of the following graphs between pressure 'p' versus volume 'V' represents the maximum work done?

Which of the following represents the correct trend for the mentioned property?
A. F $>$ P $>$ S $>$ B \quad -- First Ionization Energy
B. Cl $>$ F $>$ S $>$ P \quad -- Electron Affinity
C. K $>$ Al $>$ Mg $>$ B \quad -- Metallic character
D. K₂O $>$ Na₂O $>$ MgO $>$ Al₂O₃ \quad -- Basic character
Choose the correct answer from the options given below:

MnO₄²⁻, in acidic medium, disproportionates to:

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.

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

In Carius method, 0.75 g of an organic compound gave 1.2 g of barium sulphate, find percentage of sulphur (molar mass 32 g mol⁻¹). Molar mass of barium sulphate is 233 g mol⁻¹.

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)

Identify correct statements from the following:
A. Propanal and propanone are functional isomers.
B. Ethoxyethane and methoxypropane are metamers.
C. But-2-ene shows optical isomerism.
D. But-1-ene and but-2-ene are functional isomers.
E. Pentane and 2, 2-dimethyl propane are chain isomers.
Choose the correct answer from the options given below:

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)

Elements P and Q form two types of non-volatile, non-ionizable compounds PQ and PQ\(_2\). When 1 g of PQ is dissolved in 50 g of solvent 'A', \(\Delta T_b\) was 1.176 K while when 1 g of PQ\(_2\) is dissolved in 50 g of solvent 'A', \(\Delta T_b\) was 0.689 K. (\(K_b\) of 'A' = 5 K kg mol\(^{-1}\)). The molar masses of elements P and Q (in g mol\(^{-1}\)) respectively, are: