List of top Chemistry Questions

In a first order reaction, the concentration of the reactant is reduced to 1/8 of the initial concentration in 75 minutes. The \(t_{1/2}\) of the reaction (in minutes) is (\(\log 2 = 0.30, \log 3 = 0.47, \log 4 = 0.60\))
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
The equation which represents Freundlich adsorption isotherm is (x = amount of gas, m = mass of solid)
For which of the following the \( E^\ominus (M^{3+}/M^{2+}) \) is negative?
Which of the following is used as froth stabilizer in froth floatation process?
In a colloidal solution, both the dispersed phase and dispersion medium are in liquid phase. What is the type of colloid?
1.95 g of non-volatile and non-electrolyte solute dissolved in 100 g of benzene lowered the freezing point of it by 0.64 K. The molar mass of the solute (in g mol\(^{-1}\)) (\(K_f(\text{C}_6\text{H}_6) = 5.12 \, \text{K kg mol}^{-1}\)) is
An element (atomic weight = 250 u) crystallises in a simple cubic lattice. If the density of the unit cell is \( 7.2 \, \text{g cm}^{-3} \), what is the radius (in \( \text{\AA} \)) of the atom of the element? (\(N = 6.02 \times 10^{23} \, \text{mol}^{-1}\))
Among the following compounds, which one is not responsible for the depletion of ozone layer?
At 298 K, 0.714 moles of liquid A is dissolved in 5.555 moles of liquid B. The vapour pressure of the resultant solution is 475 torr. The vapour pressure of pure liquid A at the same temperature is 280.7 torr. What is the vapour pressure of pure liquid B in torr?
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 = \(1.29 \, \text{S m}^{-1}\))
What are X, Y, Z in the following reaction sequence? But-2-ene \( \xrightarrow{X} \) Ethanoic acid \( \xrightarrow{Y} \) Ethanoyl chloride \( \xrightarrow{\text{Benzene, Anhy. AlCl}_3} \) Z
Which method is used to purify liquids having very high boiling points and liquids which decompose at or below their boiling point?
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?
Identify the incorrect order against the stated property.
At T(K), the following gaseous equilibrium is established. W + X \( \rightleftharpoons \) Y + Z The initial concentration of W is two times to the initial concentration of X. The system is heated to T(K) to establish the equilibrium. At equilibrium the concentration of Y is four times to the concentration of X. What is the value of \(K_c\)?
Compound 'X' is prepared commercially by the electrolysis of brine solution. Which of the following is not the use of 'X'?
4 mL of 'X volume' \( \text{H}_2\text{O}_2 \) on heating gives 80 mL of oxygen at STP. The value of X is
Consider the following Statement-I : \( \text{Al}_2\text{O}_3 \) is amphoteric in nature. Statement-II : \( \text{Tl}_2\text{O}_3 \) is more basic than \( \text{Ga}_2\text{O}_3 \). The correct answer is
At \(25 ^\circ\text{C}\), \(K_a\) of formic acid is \(1.8 \times 10^{-4}\). What is the \(K_b\) of \( \text{HCOO}^- \)?
The correct order of the non-metallic character among the elements B, C, N, F and Si is
The pair of molecules / ions with the same bond order value is
At what temperature (in K) the rms velocity of SO\(_2\) molecules is equal to rms velocity of O\(_2\) molecules at \(27 \, ^\circ\text{C}\)?
For one mole of an ideal gas an isochore is obtained. The slope of the isochore is \(0.082 \, \text{atm K}^{-1}\). What will be its pressure (in atm) when the temperature is 12.2 K? (R = \(0.082 \, \text{L atm mol}^{-1} \text{ K}^{-1}\)).
Consider the following A) 0.0025 B) 500.0 C) 2.0034 Number of significant figures in A, B and C respectively, are