Draw structural formula for each reaction and state the type of reaction that is occuring:

a. 4-nonene and fluorine gas
b. hexane and oxygen gas
c. pentanol and butanoic acid
d. propene and hydrogen gas

This is a radical addition. Halogens will form radicals in the presence of light or a radical initiator, like a peroxide. Usually, they attack alkanes and alkenes to give the most stable radical intermediates, but fluorine is nasty stuff and very reactive; there isn't much selectivity with radical fluorination.

Part B
This is an oxidation reaction - more commonly known as a combustion reaction. In the presence of oxygen, hexane will burn to give water and carbon dioxide.

Part C
This is a Fisher esterification reaction. In the presence of a catalytic amount of acid or base, acids and alcohols react to form esters.

Part D
As far as I know, propane and hydrogen gas will coexist perfectly happily with one another; they won't react. Alkanes are fully reduced, so hydrogen doesn't affect them.

To draw the structural formula and identify the type of reaction for each case, we need to have some background knowledge of organic chemistry. Here's how you can approach each question:

a. 4-nonene and fluorine gas:
- Start by drawing the structural formula for 4-nonene using nine carbons in a chain, with a double bond between the fourth and fifth carbon.
- Then, represent fluorine gas (F₂) by writing F bonded to F.
- The reaction between 4-nonene and fluorine gas is an example of an addition reaction, where the double bond in 4-nonene gets replaced by a single bond to a fluorine atom.

b. Hexane and oxygen gas:
- Draw the structural formula for hexane, which consists of a chain of six carbon atoms bonded to twelve hydrogen atoms.
- Represent oxygen gas (O₂) by writing O bonded to O.
- The reaction between hexane and oxygen gas is an example of a combustion reaction, where the hexane molecule combines with oxygen to produce carbon dioxide and water.

c. Pentanol and butanoic acid:
- Draw the structural formula for pentanol, which contains five carbon atoms bonded to OH group (hydroxyl group) at the end of the chain.
- Then, draw the structural formula for butanoic acid, which consists of four carbon atoms bonded to a carboxyl group (-COOH).
- The reaction between pentanol and butanoic acid is an example of an esterification reaction, where the hydroxyl group of pentanol reacts with the carboxyl group of butanoic acid to form a molecule of water and an ester.

d. Propene and hydrogen gas:
- Draw the structural formula for propene, which consists of three carbon atoms with a double bond between the first and second carbon, and a single bond between the second and third carbon.
- Then, represent hydrogen gas (H₂) by writing H bonded to H.
- The reaction between propene and hydrogen gas is an example of a hydrogenation reaction, where the double bond in propene gets replaced by a single bond to a hydrogen atom.

Remember to label all the atoms and bonds correctly, and use the proper notation for functional groups. If you're unfamiliar with these concepts, it may be helpful to consult an organic chemistry textbook or online resources to understand the structures and reactions better.