In this reaction, Copper is the element being oxidized because it is losing electrons. It starts with a neutral charge (0) and ends up with a 6+ charge. Because its charge is increasing, it is being oxidized (losing electrons).
The answer would be 2.0 x 10^-1
The atomic mass of Cs is 132.9. So the mole number of 675 g cesium is 675/132.9 = 5.08 mole. Then the answer should be 5.08 mole.
In sodium there are 11 electrons
In chlorine there are 17 electrons
There are 17 protons in chlorine
There are 11 protons in sodium
I’m not sure what an octet is I study in a British system if there’s anything else you’re not sure of search the Internet it has all the answers