Which class includes an unsaturated hydrocarbon with a ring structure?

The correct answer is aromatic hydrocarbons.

Explanation:

Aromatic compounds are named on the basis of their fragrant characteristics and are unsaturated hydrocarbon ring compositions, which demonstrate unique characteristics, comprising unusual stability because of their aromaticity.  

They are usually signified as resonance compositions comprising double and single bonds. However, the bonding is more robust in comparison to a conjugated structure, and it is more precisely signified as delocalized electron density shared among all the atoms in the ring.  

6.4 cm (max) - 25 cm (min)

answer:

the reaction is type of combination reaction.

explanation:

on the product side, there are 2 molecules of bonded to fe   which means one atom of fe are combined two molecules of . so, balanced chemical equation becomes :

this reaction follows the reaction type of combination reaction. a combination reaction is defined as chemical reaction in which reactants combines together to form a single product.