If barium was to react with oxygen to form ionic compounds, how many oxygen atoms would be needed? Explain. I NEED THIS ASAP

How does the image distance (di) of a convex lens compare with the image distance of a concave lens? a. the image distance of the convex lens is positive, and that of the concave lens is negative. b. both are negative for a virtual image. c. both are positive for a virtual image d. the image distance of the convex lens is negative, and that of the concave lens is positive.

First to answer will be the brainliest i need the answer asap

You are an astronaut working on the international space station. accidentally, you let go of the handhold and drift off towards earth. the illustration, below, includes the details of your position (not drawn to scale). i’m a little stuck on the gravitational force felt by the astronaut from the iss. a little ?