Which of the following materials would make the best lens for a microscope

What is the mass of 4 molecules of co2

If a molecule with a molecular formula of c13h18 is treated with an excess of h2 in the presence of finally divided pt metal under conditions required for maximum hydrogenation of the molecule to give a molecule with a formula c13h24, how many rings are in the molecule?

Imagine that you push on a large rock. at what point does your effort change the rock’s mechanical energy?