How does the law of conservation of matter apply to chemical equations

Hey can you me with this i really need y’all

What is the chemical name of the compound na2co3? use the list of polyatomic ions and the periodic table to you answer. a. sodium carbon oxide b. sodium carbonate c. sodium(ll) carbonate d. sodium oxalate

Show how to convert the temperature 84.7° c to kelvin. include all steps and label the final answer.