List of top Chemistry Questions

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
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?
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
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 = \(1.29 \, \text{S m}^{-1}\))
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 (\(\log 2 = 0.30, \log 3 = 0.47, \log 4 = 0.60\))
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? (\(N = 6.02 \times 10^{23} \, \text{mol}^{-1}\))
Compound 'X' is prepared commercially by the electrolysis of brine solution. Which of the following is not the use of 'X'?
Among the following compounds, which one is not responsible for the depletion of ozone layer?
Which method is used to purify liquids having very high boiling points and liquids which decompose at or below their boiling point?
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
Identify the incorrect order against the stated property.
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
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 = \(0.082 \, \text{L atm mol}^{-1} \text{ K}^{-1}\)).
At \(25 ^\circ\text{C}\), \(K_a\) of formic acid is \(1.8 \times 10^{-4}\). What is the \(K_b\) of \( \text{HCOO}^- \)?
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?
Consider the following A) 0.0025 B) 500.0 C) 2.0034 Number of significant figures in A, B and C respectively, are
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 \(K_c\)?
Consider the following reaction A(g) + 3B(g) \( \longrightarrow \) 2C(g); \( \Delta H^\ominus = -24 \) kJ. At \(25 \, ^\circ\text{C}\) if \( \Delta G^\ominus \) of the reaction is -9 kJ, the standard entropy change (in JK\(^{-1}\)) of the same reaction at same temperature is
At what temperature (in K) the rms velocity of SO\(_2\) molecules is equal to rms velocity of O\(_2\) molecules at \(27 \, ^\circ\text{C}\)?
The pair of molecules / ions with the same bond order value is
The correct order of the non-metallic character among the elements B, C, N, F and Si is
How many of the following molecules have two lone pairs of electrons on central atom? SF\(_6\), BF\(_3\), ClF\(_3\), PCl\(_5\), BrF\(_5\), XeF\(_4\), H\(_2\)O, SF\(_4\)
The de Broglie wavelength of an electron in the third Bohr orbit of H-atom is
The difference between the radii of \(3^{rd}\) and \(2^{nd}\) orbit of H-atom is x pm. The difference between the radii of \(4^{th}\) and \(3^{rd}\) orbit of \( \text{Li}^{2+} \) ion is y pm. \(y:x\) is equal to
IUPAC names of mesityl oxide and oxalic acid are respectively: