Question

when iron is burned, it combines with oxygen to form iron oxide. the table below shows the density of all of these substances.

substance	iron		iron oxide

based on the information from the data table, which of these is a correct conclusion about the burning of iron?
a. a chemical reaction does not occur because burning iron causes it to melt, which is a physical change.
b. a chemical reaction occurs because each iron atom loses mass when it is burned.
c. a chemical reaction does not occur because both iron and iron oxide have high densities.
d. a chemical reaction occurs because the density of iron is different from the density of iron oxide.

Explanation:

Burning iron forms iron oxide, a new substance, indicating a chemical reaction. Option A is wrong because burning is not melting (physical change). Option B is wrong because mass is conserved in reactions. Option C is wrong because density similarity doesn’t negate chemical change. Option D correctly links different densities (property of new substance) to chemical reaction occurrence.

Answer:

D. A chemical reaction occurs because the density of iron is different from the density of iron oxide