Answer:
Ionic bonds usually occur between metal and nonmetal ions. For example, sodium (Na), a metal, and chloride (Cl), a nonmetal, form an ionic bond to make NaCl.
Explanation:
Answer : The pH of the solution is, 9.63
Explanation : Given,
The dissociation constant for HCN = 
First we have to calculate the moles of HCN and NaCN.

and,

The balanced chemical reaction is:

Initial moles 0.1116 0.0461 0.08978
At eqm. (0.1116-0.0461) 0 (0.08978+0.0461)
0.0655 0.1359
Now we have to calculate the pH of the solution.
Using Henderson Hesselbach equation :
![pH=pK_a+\log \frac{[Salt]}{[Acid]}](https://tex.z-dn.net/?f=pH%3DpK_a%2B%5Clog%20%5Cfrac%7B%5BSalt%5D%7D%7B%5BAcid%5D%7D)
Now put all the given values in this expression, we get:


Therefore, the pH of the solution is, 9.63
4/325 = 2/unknown temperature
unknown temperature= 2/(4/325)=162.5k
Answer: Compound
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper 
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water 

Thus as it give that the red sample on being heated, a gas is released and a blue powder is left after the heating. Thus the given sample is a compound.
I'm not sure I'm sorry for that but I found this http://www.chem4kids.com/files/atom_ions.html