Is the chemical equasion NiS plus O2 equals NiO plus SO2 balanced?

Answer 1

No. Count the number of Os on the two sides.

note: the "Os" are oxygen and you need the same number of each element (each symbol in that equation).

Answer 2

The chemical equation is not balanced. To balance it, the equation should be: 2NiS + 3O2 = 2NiO + 2SO2. This equation shows that 2 nickel sulfide molecules react with 3 oxygen molecules to produce 2 nickel oxide molecules and 2 sulfur dioxide molecules.