Mosses growing on surface of rocks, producing pits in rocks. what is it mechanical or chemical?

If the density of water is 1.0 g/cm3, which of these materials would float in water, based on their densities? check all that apply. aluminum cork iron lead wax

Find the mass, in grams, of 5.00*10^23 molecules of f2

Element j is 1s 2s 2p 3s . (i) how many unpaired electrons does j have? (ii) is j a good oxidizing agent or a reducing agent? (iii) state reason for the answer.