Knowing that the Chemistry of lanthanoids (Ln) is dominated by its +3 oxidation state, which of the following statements is incorrect?

In context with the transition elements, which of the following statements is incorrect ?

The half life period of a first order chemical reaction is 6.93 minutes. The time required for the completion of 99% of the chemical reaction will be (log 2=0.301) :

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is
CH₃OH(l) + 3/2O₂ $$\to$$ CO₂ (g) + 2H₂O (l)
At 298K standard Gibb’s energies of formation for CH₃OH(l), H₂O(l) and CO₂ (g) are -166.2, -237.2 and -394.4 kJ mol⁻¹ respectively. If standard enthalpy of combustion of methanol is -726 kJ mol⁻¹, efficiency of the fuel cell will be