The type of reaction of Fe2O3 + 2SiO2 → Fe2Si2O7 would be that it is a synthesis reaction. It is a type of chemical reaction in which two or more simple substances combine to form a more complex product. Hope this answers the question.
The gas will obey Boyles Law:
P1 V1 = P2 V2 where P1 and V1 are the original pressure and volume and P2 and V2 are the new values.
If V2 = 2V1 (given) then:
P1 V1 = P2 *2 V1
P2 = P1 V1 / 2V1
P2 = P1 / 2
In other words the pressure is halved. (answer).
Answer:
• One mole of oxygen is equivalent to 16 grams.
→ But at STP, 22.4 dm³ are occupied by 1 mole.

When two element combine to form more than one compound i hope this helps you with work have a nice day :)