What process indicates that smelting copper is a chemical change?

What makes something thinner or weaker by adding water or another liquid? How fast does water evaporate in a container? Give example of the types of problems chemists are trying to address within each area of research? How many animals can live on 11 acres? What is the collective term for the sterile leaves of a flower? Why was sandy upset with Danny when she saw him at her new school? In measuring volume of liquid why is there a need to remove traces of grease in the graduated cylinder? Mixtures which are not mixed evenly and each component retains its own properties are called what? What effect does the ozone's absorption of ultraviolet radiation have on the stratosphere? How many ounces are there in 610 grams? Is there a time difference between Delhi and Kolkata? Where can fetal pig diagrams be found? Why do you hold the stopper from the bottle between your fingers when pouring a liquid? What aerosols deplete ozone? In which cities windstorms occur? What time is the noon? What is the characteristic difference between a beam of light and a ray of light? How large is the Serengeti ecosystem? What three things does the seed consist of? What is the name for polished limestone?