Help identify these sets/bricks
01)  Bionicle piece ??? 

Part #98141 Minifigure, Weapon Crescent Blade, Serrated with Bar, with an updated and correct answer provided by site member Phil B. 



02) Part #4150 Tile, Round 2 x 2.



3 + 4) Hails from Set #76109 Quantum Realm Explorers.


The yellowed outlined pieces in 3 and 4 is Part #17485 Brick, Round 2 x 2 with Pin Holes.  

HERE's a Youtube speed build on the piece breakdown/buildup of this design look you're interested in.