When does calcium follow the octet rule when reacting to form a compound.

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.

Host danny boyle used a line from what shakespearean play to welcome the athletes and fans arriving in london for the 2012 olympics?

Acheetah ran 75 meters at a speed of 25 meters per second. how long was the cheetah running? 3 seconds 5 seconds 30 seconds 50 seconds