A crystalline solid (A) reacts with hydrogen gas to form a monoatomic gas (B) and a highly associated liquid ( C).(A) is soluble in water and undergoe

A crystalline solid (A) reacts with hydrogen gas to form a monoatomic gas (B) and a highly associated liquid ( C).(A) is soluble in water and undergoes hydroloysis slowly to form (B),(C ) and a diatomic gas (D).When pure and dry (D) is subjected to a silent electric discharge an another pale blue gas (E) is produced which like (A) also acts a strong oxidising agent.(E) dissolves in potassium hydroxide forming an orange coloured solid which is paramagnetic in nature. (A) reacts with `IF_5, SbF_5, PF_5` etc to form the addition compounds. (C ) forms an addition compound (F) with KF with when electrolysed in molten state forms a most reactive gas (G).(B) and (G) (taken in 2:1) ratio when heated in nickel tube at `400^@ C` and 6 atm pressure forms (A).The first ionization energy `(IE_1)` of (B) is fairly close to (D).
Gas (G) is produced by reacting `K_2 MnF_6` with:
A. `SbF_5`
B. `MnF_3`
C. `KSbF_5`
D. `MnF_5`