Enthalpy change for the reaction,

4H (g) → 2H₂ (g) is - 869.6 kJ

The dissociation energy of H - H bond is

• -869.6 kJ

• +434.8 kJ

• +217.4 kJ

• +217.4 kJ

A buffer solution is prepared in which the concentration of NH₃ is 0.30 M and the concentration of NH₄ is 0.20 M. If the equilibrium constant, K_b for NH₃ equals 1.8 x 10^-5, what is the pH of this solution?

log ( 2.7 = 0.43)

• 9.43

• 11.72

• 8.73

• 8.73

The Correct order of increasing bond length of C - H, C-O, C - C and C = C is

• C - C < C=C < C - O < C - H

• C - O < C - H < C - C < C = C

• C - H < C - O <  C - C < C= C

• C - H < C - O <  C - C < C= C

If the enthalpy change for the transition of liquid water to steam is 30kJ mol^-1 at 27^oC, the entropy change for the process would be. 

• 1.0 J mol^- K^-1

• 0.1 J mol^-1 K^-1

• 100 J  mol^-1 K^-1

• 100 J  mol^-1 K^-1

Which of the two ions from the list given below have the geometry that is explained by the same hybridization of orbitals,

Two gases A and B having the same volume diffuse through a porous partition in 20 and 10 seconds respectively. The molecular mass of A is 49u. Molecular mass of B will be

• 12.25 u

• 6.50 u 

• 25.00 u

• 25.00 u

7.

Which of the following is the correct option for free expansion of an ideal gas under an adiabatic condition?

• 
• 
• 
• 

A gaseous mixture was prepared by taking equal moles of CO and N₂, If the total pressure of the mixture was found 1 atmosphere, the partial pressure of the nitrogen (N₂) in the mixture is

• 0.8 atm

• 0.9 atm

• 1 atm

• 1 atm

If x is the amount of adsorbate and m is the amount of adsorbent, which of the following relations is not related to adsorption process?

• 

• p = f(T) at constant (x/m)

• 
• 

Which of the following is least likely to behave as Lewis base? 

• NH₃

• BF₃

• OH^-

• OH^-