NaNO3 ———> **heat above the arrow** NaNO2 + O2
1. What kind of reaction is the one above? *
O A. Single replacement
O B. Double replacement
O C. Composition aka synthesis
O D. Decomposition
O E. Organic combustion

D (Decomposition)

Explanation:

This reaction is a decomposition reaction because one substance (NaNO3) is being separated into two substances (NaNO2 and O2). Alternatively, you could use the process of elimination. The reaction can't be single/double replacement because there's only one reactant, it can't be synthesis because substances are being broken down, not formed, and it can't be combustion because O2 is a product, not a reactant, and CO2 and H2O aren't being produced, as is common with combustion reactions.

the answer is c.the valence of the atoms combine .