A) This is a hydrogenation reaction of an alkyne (propyne) with hydrogen. Assuming complete hydrogenation, the triple bond is reduced to a single bond, forming an alkane.

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a) This is a hydrogenation reaction of an alkyne (propyne) with hydrogen. Assuming complete hydrogenation, the triple bond is reduced to a single bond, forming an alkane.

$$\text{H}-\text{C}\equiv\text{C}-\text{CH}_3 + 2\text{H}_2(\text{g}) \xrightarrow{\text{Ni or Pt catalyst}} \boxed{\text{CH}_3-\text{CH}_2-\text{CH}_3(\text{g})}$$

b) This is an addition reaction of an alkene (1-butene) with hydrogen bromide. This reaction follows Markovnikov's Rule, where the hydrogen atom adds to the carbon of the double bond with more hydrogen atoms, and the bromine atom adds to the carbon with fewer hydrogen atoms.

$$\text{CH}_3-\text{CH}_2-\text{CH}=\text{CH}_2 + \text{HBr} \longrightarrow \boxed{\text{CH}_3-\text{CH}_2-\text{CH}(\text{Br})-\text{CH}_3}$$

c) This is an esterification reaction between an alcohol (ethanol) and a carboxylic acid (formic acid). An ester and water are formed.

$$\text{C}_2\text{H}_5\text{OH}(\text{aq}) + \text{HCOOH} \rightleftharpoons \boxed{\text{HCOOC}_2\text{H}_5(\text{aq}) + \text{H}_2\text{O}(\text{l})}$$