The element which liberates oxygen gas from water is

Which of the following arrangements does not represent the correct trend indicated against it?

Which of the following is incorrectly matched?

Which of the following processes cannot produce $Cl_2$ gas?

Arrange the following in the order of property indicated for each set:
$(i)$ $F_{2}, Cl_{2}, Br_{2}, I_{2}$ - increasing bond dissociation enthalpy.
$(ii)$ $HF, HCl, HBr, HI$ - increasing acid strength.
$(iii)$ $NH_{3}, PH_{3}, AsH_{3}, SbH_{3}, BiH_{3}$ - increasing base strength.

Compound $A$ and $B$ respectively are :-
$Cl_2 + 2NaOH (cold \& dil.) \rightarrow A + NaCl + H_2O$
$3Cl_2 + 6NaOH (hot \& conc.) \rightarrow B + 5NaCl + 3H_2O$