Question

in single - replacement reactions, a single element replaces a similar element in a compound.
in this generalized reaction, a metal replaces a metal.
ab + c → cb + a
a non - metal can also replace a non - metal.
ab + d → ad + b
in both generalized reactions, the compounds are typically aqueous. this means the compounds are dissolved in water.
describe what the circles and squares represent in the generalized reaction.

Explanation:

In single - replacement reactions shown, circles and squares represent elements. In the first reaction, a metal (circle) replaces another metal in a compound. In the second, a non - metal (square) replaces a non - metal in a compound. So, circles represent elements that can participate in single - replacement reactions as metals or non - metals, and squares represent elements that can participate as non - metals in single - replacement reactions.

Answer:

Circles represent elements (metals or non - metals in single - replacement reactions), squares represent non - metals in single - replacement reactions.