Question

question 1
c₃h₈ + 5 o₂ --> 3 co₂ + 4 h₂o
decomposition reaction
single replacement reaction
combustion reaction
double replacement reaction
synthesis reaction
question 2
2 c₂h₂ + 5 o₂ --> 4 co₂ + 2 h₂o
combustion reaction
double replacement reaction
synthesis reaction
single replacement reaction
decomposition reaction
question 3
4 cr + 3 o₂ --> 2 cr₂o₃
synthesis reaction
decomposition reaction
single replacement reaction
combustion reaction
double replacement reaction

Explanation:

Question 1

The reaction is \( \ce{C3H8 + 5O2 -> 3CO2 + 4H2O} \). Combustion reactions involve a hydrocarbon (like \( \ce{C3H8} \), propane) reacting with oxygen to produce \( \ce{CO2} \) and \( \ce{H2O} \). Decomposition is breaking down a compound, single replacement is one element replacing another, double replacement is two compounds exchanging ions, and synthesis is combining substances. This fits combustion.

The reaction is \( \ce{2C2H2 + 5O2 -> 4CO2 + 2H2O} \). \( \ce{C2H2} \) (acetylene) is a hydrocarbon reacting with \( \ce{O2} \) to form \( \ce{CO2} \) and \( \ce{H2O} \), which is the pattern of a combustion reaction. Other reaction types don't match (e.g., synthesis is combining, replacement reactions involve element - compound interactions, decomposition is breaking down).

The reaction is \( \ce{4Cr + 3O2 -> 2Cr2O3} \). A synthesis reaction is when two or more substances combine to form a single product. Here, \( \ce{Cr} \) and \( \ce{O2} \) combine to form \( \ce{Cr2O3} \). Decomposition is the opposite, replacement reactions involve element - compound interactions, and combustion typically involves hydrocarbons with \( \ce{O2} \) (this has a metal and \( \ce{O2} \), not a hydrocarbon).

Answer:

Combustion reaction

Question 2