I have 3 questions 1. How many molecules of alumina (Al2O3) will be formed by burning 32.4 g of aluminum? How many grams of oxygen were involved in the reaction?
2. How many grams of sodium were involved in the reaction with 30.53 g of chlorine (Cl2)? How Many Grams and Moles of Sodium Chloride (NaCl) Are Formed?
3. How many grams of silver were involved in the reaction with 12.8 g of oxygen (O2)? How many grams and moles of silver oxide (Ag2O) are formed?

I don't know if this is that understandable because i translated the text from another language to English

Achemical reaction (also known as a chemical change) produces substances that are chemically different from the starting materials. an example of a chemical reaction is the formation of water from hydrogen and oxygen gas.in a physical change, a substance changes its physical appearance but not its chemical identity. an example of physical change is the formation of liquid water from solid water, a familiar process called melting. physically, liquid water looks very different from solid water (ice) but the chemical identity, water, is the same for both. which of following changes that affect the composition of our atmosphere involve physical changes and which involve chemical reactions? oxygen gas changes to ozone during thunderstorms carbon dioxide is produced by the combustion of gasoline in an automobile engine. when coal, oil, and natural gas are decomposed in landsills they produce methane gas. freezing rain develops when a warm air mass overrides a cold air mass. fog forms from water vapor when the temperature drops below the dew point

Use examples from the article to explain one positive and one negative effect that chemistry has had on society.

How are isotopes of the same chemical element alike? how are they different?