List of top Chemistry Questions

Which out of NH3 and NF3 has higher dipole moment and why?
A solution of glucose in water is labelled as \(10\%\) \(\text{w/w}\), what would be the molality and mole fraction of each component in the solution? If the density of solution is \(1.2\, \text{g mL}^{–1}\), then what shall be the molarity of the solution?
The work function for caesium atom is 1.9 eV. Calculate (a) the threshold wavelength and (b) the threshold frequency of the radiation. If the caesium element is irradiated with a wavelength 500 nm, calculate the kinetic energy and the velocity of the ejected photoelectron.
Concentrated nitric acid used in laboratory work is \(68\%\) nitric acid by mass in aqueous solution. What should be the molarity of such a sample of the acid if the density of the solution is \(1.504\, \text{g mL}^{–1}?\)
Give an example of a solid solution in which the solute is a gas.
The longest wavelength doublet absorption transition is observed at 589 and 589.6 nm. Calculate the frequency of each transition and energy difference between two excited states.
Write Lewis dot symbols for atoms of the following elements: Mg, Na, B, O, N, Br.
In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of 3.15 × 10–18 J from the radiations of 600 nm, calculate the number of photons received by the detector.
Explain why pure liquids and solids can be ignored while writing the equilibrium constant expression?
For the following equilibrium, \(K_c = 6.3 × 10^{14}\) at \(1000\  K\)
\(NO (g) + O_3 (g) ⇋ NO_2 (g) + O_2 (g)\)
Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is \(K'_c\) for the reverse reaction?
Apart from tetrahedral geometry, another possible geometry for CH4 is square planar with the four H atoms at the corners of the square and the C atom at its centre. Explain why CH4 is not square planar?
The skeletal structure of CH3COOH as shown below is correct, but some of the bonds are shown incorrectly. Write the correct Lewis structure for acetic acid.
The skeletal structure of CH3COOH
Arrange the bonds in order of increasing ionic character in the molecules: LiF, K2O, N2, SO2 and ClF3.
Explain with the help of suitable example polar covalent bond.
Define electronegativity. How does it differ from electron gain enthalpy?
Write the expression for the equilibrium constant, Kc for each of the following reactions: 
  1. \(2NOCl (g) ⇋ 2NO (g) + Cl_2 (g)\)
  2. \(2Cu(NO_3)_2 (s) ⇋ 2CuO (s) + 4NO_2 (g) + O_2 (g)\)
  3. \(CH_3COOC_2H_5(aq) + H_2O(l) ⇋ CH_3COOH (aq) + C_2H_5OH (aq)\)
  4. \(Fe^{3+} (aq) + 3OH^– (aq) ⇋ Fe(OH)_3 (s)\)
  5. \(I_2 (s) + 5F_2 ⇋ 2IF_5\)
Write the significance/applications of dipole moment.
Find out the value of \(K_c\) for each of the following equilibria from the value of \(K_p\): 
  1. \(2NOCl (g) ⇋ 2NO (g) + Cl_2 (g); \ K_p= 1.8 × 10^{–2}\  at \ 500\ K\)
  2. \(CaCO_3 (s) ⇋ CaO(s) + CO_2(g); \ K_p= 167 \ at \ 1073\  K\)
Use Lewis symbols to show electron transfer between the following atoms to form cations and anions:
  1. K and S 
  2. Ca and O 
  3. Al and N.
Explain the important aspects of resonance with reference to the \(CO_3^{2-}\) ion.
Although geometries of NH3 and H2O molecules are distorted tetrahedral, bond angle in water is less than that of ammonia. Discuss.
Define octet rule. Write its significance and limitations.
Considering the elements F, Cl, O and N, the correct order of their chemical reactivity in terms of oxidizing property is:
At a certain temperature and total pressure of 105 Pa, iodine vapour contains 40% by volume of \(\text {I}\) atoms
\( I_2 (g) ⇋ 2I (g)\)
Calculate Kp for the equilibrium.
Considering the elements B, C, N, F, and Si, the correct order of their non-metallic character is: