. The power of a double convex lens is 10D and the radius of curvature of each surface is 10cm. what is the refractive index of the material.

i was thinking more like reflects green light, just not sure

a lot of it means it can be "burned" for energy and sold at one price. if it is scarce, the price will go up

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me

there are no components of a physical goal mentioned on the list of choices that you've provided.