A rocket engine is able to produce thrust on a spacecraft. Identify the correct action-reaction pair which allows the spacecraft to propel itself upward before it heads to space.

Sat no calculator section question in the picture

Earth's atmosphere is unique among the planets and is able to support life because it contains a large amount of a) oxygen b) helium c) methane d) carbon dioxide

Which statements are true for invasive species? 1. they always stabilize an ecosystem. 2. they’re always successful in adjusting to a new habitat. 3. they often compete with the native species for resources. 4. they have the ability to displace the native species. 5. they’re always pests.