Can someone help me ?

Explanation:

The Stock System states that In a chemical formula or equation, some metals need a roman numeral after their symbol. If a metal has multiple oxidation states, it needs a roman numeral.

Use the Periodic Table to see the oxidation states for each metal.

We can see that cobalt, iron, and copper have more than one oxidation state, so they would require a roman numeral.

> b takes place in the gas phase in an isothermal tubular reactor. the feed is one mole of a per one mole of c, an inert. the entering temperature and pressure are 427°c and 10 atm, respectively. the gas constant r = 0.08206 atm · l/mol · k.