List of top Chemistry Questions

Which of the following orders is not correct about the property shown against it?
The standard enthalpy of formation of C\(_2\)H\(_4\)(g), CO\(_2\)(g), and H\(_2\)O(l) are 52, –394, and –286 kJ mol\(^{-1}\) respectively. The heat evolved by burning 7 g of C\(_2\)H\(_4\)(g) is
Observe the following molecules: ClF, SF$_4$, CH$_4$, NH$_3$, XeF$_4$, PCl$_5$. The number of molecules in which the central atom has expanded octet is:
White phosphorus on heating with concentrated NaOH solution in an inert atmosphere of CO\(_2\) gives a salt 'X' and gas 'Y'. The oxidation state of central atom in X and Y is respectively
One mole of \( \text{C}_2\text{H}_5\text{OH(l)} \) was completely burnt in oxygen to form \( \text{CO}_2\text{(g)} \) and \( \text{H}_2\text{O(l)} \). The standard enthalpy of formation (\( \Delta_f H^\ominus \)) of \( \text{C}_2\text{H}_5\text{OH(l)} \), \( \text{CO}_2\text{(g)} \) and \( \text{H}_2\text{O(l)} \) is x, y, z kJ mol\(^{-1}\) respectively. What is \( \Delta_r H^\ominus \) (in kJ mol\(^{-1}\)) for this reaction?
The sum of number of antibonding electrons present in O$_2$, O$_2^+$, O$_2^-$ is:
For which of the following the \( E^\ominus (M^{3+}/M^{2+}) \) is negative?
Bithionol is added to soaps to impart antiseptic properties. The number of –OH and –Cl groups in its structure are respectively
At temperature \(T(K)\), the solubility product of AgBr is \(4 \times 10^{-13}\). What is its solubility in 0.1 M KBr solution?
Ammonium chloride on reaction with calcium hydroxide gives a gas X. The incorrect statement about X is
The alloy that contains copper and Zn is $x$ and the one that contains copper and Ni is $y$. What are $x$ and $y$ respectively?
Consider the following.
Statement-I: Gold sol is prepared by Bredig’s arc method.
Statement-II: Bredig’s arc method involves only dispersion but not condensation.
Activation energy for the hydrolysis of sucrose by acid is X kJ mol$^{-1}$ and by sucrase is Y kJ mol$^{-1}$. X and Y respectively are
For which reaction \( \Delta H \neq \Delta U \)?
Which of the following is an example of a negatively charged sol?
The resistance of a conductivity cell filled with 0.1 M KCl solution is \(100 \, \Omega\). If the resistance of the same cell when filled with 0.02 M KCl solution is \(520 \, \Omega\), the molar conductivity of 0.02 M solution (in S cm\(^2\) mol\(^{-1}\)) is (Given: conductivity of 0.1 M KCl solution = \(1.29 \, \text{S m}^{-1}\))
The correct equation for one mole of a real gas is (a, b are constants)
What are X and Y respectively in the following reaction sequence? (\(anhy = \text{anhydrous}\)) \[ \text{C}_6\text{H}_5\text{N}_2^+\text{X}^- \xrightarrow{\text{C}_2\text{H}_5\text{OH}} \text{X} \xrightarrow{\text{CO, HCl, anhy. AlCl}_3} \text{Y} \] % The question implies the first X is an anion, the second X is an organic product. Let's call the organic product P1 to avoid confusion. % So, C6H5N2+Anion- → P1 → Y
Sucrose when boiled with dilute HCl gives two functional isomers X and Y. X gives monocarboxylic acid with bromine water but not Y. The number of --OH groups in cyclic structure of X is
In which of the following intramolecular H-bonding is absent?
Options:
- Salicylic acid
- Salicylaldehyde
- Quinol
- Catechol
For a first-order reaction, the rate constant \( k \) is \( 1.386 \times 10^{-3} \, \text{s}^{-1} \). What is the half-life \( t_{1/2} \) of the reaction? (Use \( \ln 2 = 0.693 \))
At $T(K)$, the vapor pressure of water is $x$ kPa. What is the vapor pressure (in kPa) of 1 molal solution containing non-volatile solute?

Match the following: 



 

Among \( \text{B}_2\text{O}_3 \), \( \text{Al}_2\text{O}_3 \), and \( \text{In}_2\text{O}_3 \), the oxides which react with alkalies are:
The number of molecules having lone pair of electrons on central atom in the following is: BF$_3$, SF$_4$, SiCl$_4$, XeF$_4$, NCl$_3$, XeF$_6$, PCl$_5$, HgCl$_2$, SnCl$_2$