Answer: The element Na (Sodium) is getting oxidized and Hydrogen is getting reduced.
Explanation:
Oxidation reactions are the reactions in which addition of oxygen takes place.
Reduction reactions are the reactions in which loss of oxygen takes place.
For a given reaction:

Sodium is getting oxidized because there is an addition of reaction with that element.
Hydrogen is getting reduced because there is a removal of oxygen with that element.
Moles of NaN3 at STP = volume of gas / 22.4 = 11.5/22.4 = 0.5mole. Massof NaN3 = moles of NaN3 x molecular weight = 0.5 x 65 = 32.5 grams.
Answer:
16 is the mass number. 8 is the atomic number.
1.Calcium Chloride
2.Lithium Bromide
3.Beryllium Sulfide
4.Lithium Fluoride
5. Potassium hydroselenide
6. Strontium phosphide
7.Barium Chloride
8.Iron Oxide
9.Iron
10.?
11.Copper Nitride