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.
Answer:
Explanation:
If you insist on filling in the first blank you can put a one.
The correct formula for carbon disulfide - CS2
Hope it helped!
Magma is made of molten rock. Melted of molten rock. Answer is rock.