When O₂ is adsorbed on a metallic surface, electron transfer occurs from the metal to O₂. The true statement(s) regarding this adsorption is(are)

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When 100 mL of 1.0 M KCl was mixed with 100 mL of 1.0 M NaOH in an insulated beaker at constant pressure, a temperature increase of 5.7^o C was measured for the beaker and its contents (Expt. 1). Because the enthalpy of neutralization of a strong acid with a strong base is constant (-57.0 kJ/mol), this experiment could be used to measure the calorimeter constant. In a second experiment (Expt. 2) 100 mL of 2.0 M acetic acid (K_a = 2.0 $$\times$$ 10^-5) was mixed with 100 mL of 1.0 M NaOH (under identical conditions to Expt. 1) where a temperature rise of 5.6^o C was measured. (Consider heat capacity of all solutions as 4.2 J/gK and density of all solutions as 1.0 g m/L)
Question
The pH of the solution after Expt. 2 is

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When 100 mL of 1.0 M HCl was mixed with 100 mL of 1.0 M NaOH in an insulated beaker at constant pressure, a temperature increase of 5.7^o C was measured for the beaker and its contents (Expt. 1). Because the enthalpy of neutralization of a strong acid with a strong base is constant (-57.0 kJ/mol), this experiment could be used to measure the calorimeter constant. In a second experiment (Expt. 2) 100 mL of 2.0 M acetic acid (K_a = 2.0 $$\times$$ 10^-5) was mixed with 100 mL of 1.0 M NaOH (under identical conditions to Expt. 1) where a temperature rise of 5.6^o C was measured. (Consider heat capacity of all solutions as 4.2 J/gK and density of all solutions as 1.0 g m/L)
Question
Enthalpy of dissociation (in kJ/mol) of acetic acid obtained from the Expt. 2 is

The number of hydroxyl group(s) in Q is ___________.