Answer:
Valence electrons of selenium will be placed in s and p-orbitals.
Explanation:
Hope this helps.
Answer:
Ammonium chloride
Explanation:
The powder is:- Ammonium chloride
When mixed with silver nitrate, white prescipitate of silver chloride is formed as:-

When mixed with sodium hydroxide, ammonia gas is formed which has noxious order.

Ammonia gas on reaction with nickel (II) hydroxide forms deep blue colored complex as shown below:-
![Ni(OH)_2(s) + 6NH_3(aq)\rightarrow [Ni(NH_3)_6]^{2+}(aq) + 2OH^{-}(aq)](https://tex.z-dn.net/?f=Ni%28OH%29_2%28s%29%20%2B%206NH_3%28aq%29%5Crightarrow%20%5BNi%28NH_3%29_6%5D%5E%7B2%2B%7D%28aq%29%20%2B%202OH%5E%7B-%7D%28aq%29)
It’s a exothermic reaction.