List of top Chemistry Questions

Identify the correct order of organic compounds in the following chemical reaction:

(A) CH₃MgBr
(B) CH₃Br
(C) CH₃Cl
(D) CH₄
Choose the correct answer from the options given below:

A solid is dissolved in 1 L water. The enthalpy of its solution ($\Delta H_{{sol}}^\circ$) is 'x' kJ/mol. The hydration enthalpy ($\Delta H_{{hyd}}^\circ$) for the same reaction is 'y' kJ/mol. What is lattice enthalpy ($\Delta H_{{lattice}}^\circ$) of the solid in kJ/mol?

Which of the following compounds does not show Lassaigne’s test for nitrogen? (A) Urea
(B) Hydrazine
(C) Phenylhydrazine
(D) Azobenzene

A molecule X associates in a given solvent as per the following equation:
X ⇌ (X)_n
For a given concentration of X, the van’t Hoff factor was found to be 0.80 and the
fraction of associated molecules was 0.3. The correct value of ‘n’ is:

A solution is prepared by dissolving 5 g of a non-volatile solute in 200 g of water. It has a vapor pressure of 31.84 mm Hg at 300 K. Calculate the molar mass of the solute.
(Vapor pressure of pure water at 300 K = 32 mm Hg)

If 75$\%$ of a first-order reaction gets completed in 32 minutes, the time taken for 50$\%$ completion of this reaction is:

Identify the major product C formed in the following reaction sequence:

Consider the reaction: $C_2H_5Cl(g) \rightarrow 2C(g) + 5H(g) + Cl(g)$, where $\Delta H = 3047 \, {kJ mol}^{-1}$. The bond dissociation enthalpy ($\Delta_{{bond}} H$) values of C–Cl and C=C bonds are 431 and 414 kJ mol$^{-1}$, respectively. What is the average bond enthalpy of C–H in kJ mol$^{-1}$?

If the first ionisation enthalpy of Li, Be and C respectively are 520, 899, 1086 kJ/mol, the first ionisation enthalpy (in kJ/mol) of B will be

Among the following, the correct statement(s) for electrons in an atom is(are)

The vapour pressures of A and B at 25°C are 75 mm Hg and 25 mm Hg, respectively. If A and B are mixed such that the mole fraction of A in the mixture is 0.4, then calculate the mole fraction of B in the vapour phase.

An organic compound $P$ with molecular formula $C_6H_6O_3$ gives a ferric chloride test and does not have an intramolecular hydrogen bond. The compound $P$ reacts with 3 equivalents of $NH_2OH$ to produce oxime $Q$. Treatment of $P$ with excess methyl iodide in the presence of $KOH$ produces compound $R$ as the major product. Reaction of $R$ with excess iso-butylmagnesium bromide followed by treatment with $H_3O^+$ gives compound $S$ as the major product. The total number of methyl ($-CH_3$) groups in compound $S$ is \_\_\_\_\_.

An organic compound P having molecular formula C₆H₆O₃ gives ferric chloride test and does not have intramolecular hydrogen bond. The compound P reacts with 3 equivalents of NH₂OH to produce oxime Q. Treatment of P with excess methyl iodide in the presence of KOH produces compound R as the major product. Reaction of R with excess iso-butylmagnesium bromide followed by treatment with H₃O⁺ gives compound S as the major product.
The total number of methyl (−CH₃) group(s) in compound S is ____.

The vapour pressure of H$_2$O at 323K is 95 mm of Hg. 176g of sucrose (Molar mass = 342 gmol$^{-1}$) is added to 900g of H$_2$O at 323K.
The vapour pressure of solution is about

An alkene X ($ C_4H_8 $) on reaction with HBr gave Y ($ C_4H_9Br $). Reaction of Y with benzene in the presence of anhydrous $ AlCl_3 $ gave Z which is resistant to oxidation with $ KMnO_4 + KOH $. What are X, Y, Z respectively?

How many electrons are involved in the following redox reaction? \[ \text{Cr}_2\text{O}_7^{2-} + \text{Fe}^{2+} + \text{C}_2\text{O}_4^{2-} \rightarrow \text{Cr}^{3+} + \text{Fe}^{3+} + \text{CO}_2 \quad (\text{Unbalanced}) \]

Ionic bond is formed due to transfer of electrons from

When n-hexane is heated to 773K at 10-20 atmosphere pressure in the presence of $Cr_2O_3$, benzene is formed. This reaction is called

At 400 K, an ideal gas is enclosed in a 0.5 m$^3$ vessel at a pressure of 203 kPa. What is the change in temperature required (in K), if it occupies a volume of 0.2 m$^3$ under a pressure of 304 kPa? (Nearest integer)

Which of the following statement is correct?

The quantum number which determines the shape of the subshell is:

A compound X contains 32% of A, 20% of B and remaining percentage of C. Then, the empirical formula of X is:
(Given atomic masses of A=64; B=40; C=32 u)

The work done during reversible isothermal expansion of one mole of hydrogen gas at 25^oC from a pressure of 20 atm to 10 atm is:
(Given R = 2.0 cal K^-1 mol^-1)

Given below are certain cations. Using inorganic qualitative analysis, arrange them in increasing group number from 0 to VI.
A) Al³⁺
B) Cu²⁺
C) Ba²⁺
D) Co²⁺
E) Mg²⁺
Choose the correct answer from the options given below

Identify the incorrect statement.