To determine which of the given options represents the combustion of a hydrocarbon, we need to recall what combustion of a hydrocarbon entails. Combustion of a hydrocarbon is a chemical reaction where a hydrocarbon reacts with oxygen (O₂) to produce carbon dioxide (CO₂) and water (H₂O). Let's analyze each option step-by-step:
Option A: [tex]$NaOH + HCl \rightarrow NaCl + H _2 O$[/tex]
This equation represents a neutralization reaction between sodium hydroxide (a base) and hydrochloric acid (an acid) to produce sodium chloride (a salt) and water. This is not a combustion reaction.
Option B: [tex]$CO _2+ H _2 O \rightarrow H _2 CO _3$[/tex]
This equation describes the formation of carbonic acid from carbon dioxide and water. It’s a process commonly associated with the dissolution of CO₂ in water but is not related to the combustion of a hydrocarbon.
Option C: [tex]$C _2 H _4+ Cl _2 \rightarrow C _2 H _4 Cl _2$[/tex]
This equation shows an addition reaction where ethene reacts with chlorine to form 1,2-dichloroethane. Again, this is not a combustion reaction.
Option D: [tex]$ \mathbf{2 C _2 H _2 + 5 O _2 \rightarrow 4 CO _2 + 2 H _2 O} $[/tex]
Let's analyze this reaction carefully:
- [tex]$2 C_2 H_2$[/tex] is acetylene, a hydrocarbon.
- [tex]$5 O_2$[/tex] is oxygen.
- The products are [tex]$4 CO_2$[/tex] (carbon dioxide) and [tex]$2 H_2 O$[/tex] (water).
This follows the format of a combustion reaction: hydrocarbon + oxygen → carbon dioxide + water.
Therefore, the reaction shown in Option D is indeed the combustion of a hydrocarbon.
So, the correct answer is:
D. [tex]$2 C _2 H _2 + 5 O _2 \rightarrow 4 CO _2 + 2 H _2 O$[/tex]
