Final answer:
To identify an oxyanion in a compound, look for the suffixes -ate or -ite, which denote the presence of an oxygen-containing anion with a relative number of oxygen atoms.
Step-by-step explanation:
The ending name that helps you identify the presence of an oxyanion in a compound is -ate or -ite. For example, sulfurous acid has the formula H2SO3 and contains the oxyanion sulfite (SO32-), which has one fewer oxygen than sulfate (SO42-). Therefore, the correct answer to the question is option c) -ate, and option d) -ite. The suffix -ate denotes an oxyanion with a larger number of oxygen atoms, while the suffix -ite indicates an oxyanion with fewer oxygen atoms as compared to the corresponding -ate form.