Which crustal change involves the release of large amounts of heat

What are the primary responsibilities of a chemical engineer involved in "r& d"? develop large scale manufacturing operations discover new products and processes training of new chemists determine products needed by consumers

Silver tarnishes as silver metal reacts with hydrogen sulfide, h2s, in the air. in this reaction, dark silver sulfide, au2s, covers the surface of silver. when silver is polished, this coating of silver sulfide can be removed from the surface. this makes the silver shiny again. enter the coefficients that balance the tarnishing reaction equation. (type 1 for no coefficient.)

Which best explains why an iceberg floats?