How can astronomers best determine the temperature of stars near us in the milky way?.

Which is not true about oxygen-17 and oxygen-18?

You throw a small rock straight up from the edge of a highway bridge that crosses a river. the rock passes you on its way down, 7.00 s after it was thrown. what is the speed of the rock just before it reaches the water 28.0 m below the point where the rock left your hand? ignore air resistance.

What component of earth’s atmosphere exists entirely as a result of photosynthesis?