Elements in the same family tend to have the same number of valence electrons.

What must students do with the 10 gird-ins on the math section of the psat

In the image, layer a is the topmost layer. layer c contains fossils from the precambrian era. layer b contains dinosaur fossils, and layer a contains fossils of mammals. which two statements are supported by this evidence? 1. mammals lived before the precambrian era. 2. dinosaurs and mammals existed in the precambrian era. 3. dinosaurs evolved after precambrian organisms. 4. precambrian organisms evolved after dinosaurs. 5. precambrian organisms were the first life-forms to become fossilized, according to this sample.

Iknow this isn't a question, but is there someway to ask a question under public safety or is there no category for it? i don't know if i'm overlooking it or not.