if i was silver 4 what would i get placed if i went 10 and 0

silver 2 or silver 1...possibly gold 5, very unlikely, but they aren't going to affect you that much like you're not going to go to mid gold from it unless you are duoing with a high elo player for all 10.

Going 10-0 against Plat/Diamond/Higher ranked player will get you a higher promotional rank than going 10-0 against all Bronze teams. It really comes down to your foes.

You should be in S4. I was in promos to Silver 1 and I got placed in Silver 5 after going 5-5 in my games.