The concentration of a chemical degrades in water according to first-order kinetics. The degradation constant is 0.2 day−1. If the initial concentration is 100.0 mg · L−1, how many days are required for the con- centration to reach 0.14 mg · L−1?

Silica, sio2, is formed on silicon as an electrically insulating layer for microelectronic devices. silica is formed when silicon is exposed to o2 gas at an elevated temperature. at 900˚c, it takes 90 minutes for the oxygen to diffuse from the surface to form a 0.06 micron (0.06 x 10-6 m) thick layer of sio2 on

How many atoms or molecules are there in a mole of a substance?

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.