Propane burns in air to produce carbon dioxide and water. what is this type of chemical reaction called?
synthesis
combustion
decomposition
single replacement

combustion

Explanation:

1. Synthesis is a chemical reaction in which two or more reactants combine to give a single product.

2. Combustion is a chemical reaction in which hydrocarbon burns in the presence of oxygen to form carbon dioxide, water and energy.

2. Decomposition reaction is a chemical reaction in which one reactant gives two or more than two products on absorption of energy.

4. A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.

what is the general relationship between a galaxy's distance from earth and its speed?

the answer is:

the farther away a galaxy is from us, the faster it is moving away from us.