A because carbon dioxide is a gas with molecules
Cobalt because it has an atomic mass of 58 and 33 neutrons.
42,256 = 2,000
42,256 = 200
together they'd be 2,200 (if that's what you needed as well)
Naming conventions for 2 non-metals like Si and O are based on their valence electrons, Si has 4 electrons around it and Oxygen has 6, in order for you to satisfy octet (8 electrons around each element) surrounding each Si and O, you need another O, To name these 2, just write the name of the first element which has less electrons first then the second element to which you use a prefix "di" since it means there are two oxygen, then put the names together and end the name of the second element with "ide" (remove the last 4 letters).
Silicon + "dI" + ox +"ide"
