Given that $∆$H_f (H) = 218 kJ/ mol, express the H-H bond energy in kcal/ mol.

• 52.15

• 911

• 104.3

• 52153

Fluorine reacts with dilute NaOH and forms a gaseous product A. The bond angle in the molecule of A is

• 104°40'

• 103°

• 107°

• 109°28'

The number of p$\mathrm{\pi }$-d$\mathrm{\pi }$ 'pi' bonds present in XeO₃ and XeO₄ molecules, respectively are-

• 3, 4

• 4, 2

• 2, 3

• 3, 2

The wavelengths of electron waves in two orbits is 3 : 5. The ratio of kinetic energy of electrons will be 

• 25 : 9

• 5 : 3

• 9 : 25

• 3 : 5

Which one of the following sets correctly represents the increase in the paramagnetic property of the ions?

• Cu²⁺ > V²⁺ > Cr²⁺ > Mn²⁺

• Cu²⁺ < Cr²⁺ < V²⁺ < Mn²⁺

• Cu²⁺ < V²⁺ < Cr²⁺ < Mn²⁺

• V²⁺ < Cu²⁺ < Cr²⁺ < Mn²⁺

Dipole moment of HCl = 1.03 D, HI= 0.38 D. Bond length of HCl = 1.3 Å and HI = 1.6 Å. The ratio of fraction of electric charge, δ, existing on each atom in HCl and HI is

• 12 : 1

• 2.7 : 1

• 3.3 : 1

• 1 : 3.3

7.

1.5 g of CdCl₂ was found to contain 0.9 g of Cd. Calculate the atomic weight of Cd.

• 118

• 112

• 106.5

• 53.25

The average kinetic energy of one molecule of an ideal gas at 27°C and 1 atm pressure is

• 900 cal K^-1 mol^-1

• 6.21 × 10^-21 JK^-1 molecule^-1

• 336.7 JK^-1 molecule^-1

• 3741.3 JK^-1 mol^-1

pH of a buffer solution decreases by 0.02 units when 0.12 g of acetic acid is added to 250 mL of a buffer solution of acetic acid and potassium acetate at 27°C. The buffer capacity of the solution is

• 0.1

• 10

• 1

• 0.4

Which one of the following order is correct for the first ionisation energies of the elements?

• B < Be < N < O

• Be < B < N < O

• B < Be < O < N

• B < O < Be < N