What element that is stable and have 3 energy levels

Ineed a good science fair name i’m doing a homemade water filter and i have no idea what the title should be plz

1. which of the following statements are true about routers and routing on the internet. choose two answers. a. protocols ensure that a single path between two computers is established before sending packets over it. b. routers are hierarchical and the "root" router is responsible for communicating to sub-routers the best paths for them to route internet traffic. c. a packet traveling between two computers on the internet may be rerouted many times along the way or even lost or "dropped". d. routers act independently and route packets as they see fit.

Per the municipal solid waste report, what are the most common sources of waste (trash