Answer:
A mixture is a physical combination of substances thus it only requires physical processes to separate. However, a compound is chemically combined and can only be separated by chemical processes. Therefore, it is much harder to separate a compound than a mixture.
Answer:
-7.34 kilo Joules is the change in enthaply when 20.0 grams of nitrogen triiodide decomposes.
Explanation:
Mass of nitrogen triiodide = 20.0 g
Moles of nitrogen triiodide = 

According to reaction, 2 moles of nitrogen triiodide gives 290.0 kilo Joules of heat on decomposition ,then 0.05063 moles of nitrogen triiodide will give :

-7.34 kilo Joules is the change in enthaply when 20.0 grams of nitrogen triiodide decomposes.
"Increase Pressure " is the right answer. if you need help , let me know
What model? can you screenshot it or send a link?