Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R

Assertion A : Beryllium has less negative value of reduction potential compared to the other alkaline earth metals.

Reason R : Beryllium has large hydration energy due to small size of Be$$^{2+}$$ but relatively large value of atomization enthalpy

In the light of the above statements, choose the most appropriate answer from the options given below :

Identify the correct statements about alkali metals.

A. The order of standard reduction potential (M$$^+$$ | M) for alkali metal ions is Na > Rb > Li.

B. CsI is highly soluble in water.

C. Lithium carbonate is highly stable to heat.

D. Potassium dissolved in concentrated liquid ammonia is blue in colour and paramagnetic.

E. All the alkali metal hydrides are ionic solids.

Choose the correct answer from the options given below :

Match List I with List II

Choose the correct answer from the options given below :

Reaction of BeO with ammonia and hydrogen fluoride gives A which on thermal decomposition gives $$\mathrm{BeF_2}$$ and $$\mathrm{NH_4F}$$. What is 'A'?