Question

in the chemical equation, fe(s) + o₂(g) → fe₂o₃(s), what is the state of matter for o₂?
solid
liquid
gas
aqueous solution
what type of reaction involves an element replacing another element in a compound one time?
single replacement
double replacement
combustion
decomposition

Explanation:

First Question (State of Matter for \( O_2 \))

In chemical equations, the state symbol in parentheses indicates the state of matter. For \( O_2 \), the symbol is \( (g) \), which stands for gas. So we identify the correct option based on this notation.

A single replacement reaction is defined as a reaction where one element replaces another element in a compound. The description "an element replacing another element in a compound one time" matches the definition of a single replacement reaction.

Answer:

C. Gas

Second Question (Type of Reaction)