When were they discovred?

What are facts about homogeneous mixtures? What is the steps for oxygen to become carbon dioxide? Is citric acid solubility in ethanol? What are the main characteristics of facilitated diffusion? Will fossil fuels ever run out? Is red litmus paper an indicator? Is lead weights a mixture compound or element? How do scientists know atoms exist if atoms are so small? When you are doing an experiment that will have multiple trials how do you handle averages chemistry? How many grams in 16 oz? Why hydrochloric acid have warning label? What term is given to the process of rearranging electrons in a semiconductor by adding atoms of other elements? How do you clean silver or brass articles that have got tarnished? What degree does sterling silver melt? Which element in the fourth period is an exception to the aufbau principle? Is energy given out when elements are formed from a compound? What is the correct chemical name for BaSO4? Enter the coefficients for each compound in order separated by commas For example 1234 would indicate one mole of C'8 H'18 two moles of O'2 three moles of CO'2 and four moles of H'2O? The currently most-accepted scientific model of the universe's beginnings is an explosion called the big bang? What is the value heat transfer coefficient of copper?

When were they discovred?