Question

allen is carrying out reactions in a lab. one of the products in all reactions is found to be either a precipitate, a gas, or water. what is common between all these reactions?
a. they are all decomposition reactions.
b. they are all combination reactions.
c. they are all combustion reactions.
d. they are all single - replacement reactions.
e. they are all double - replacement reactions.

Explanation:

Double - replacement reactions typically involve the exchange of ions between two compounds. The products of double - replacement reactions are often a precipitate (insoluble solid), a gas, or water. Decomposition reactions break down a single compound into simpler substances, combination reactions combine substances into one, combustion reactions involve burning (usually with oxygen and producing $CO_2$ and $H_2O$ but not always just precipitate/gas/water as products), and single - replacement reactions involve one element replacing another in a compound. So the reactions where products are precipitate, gas, or water are likely double - replacement reactions.

Answer:

E. They are all double - replacement reactions.