Worth 100 points and it says 50 because it is split in half but tell me what is your favorite movie

Design techniques and materials that reduce the negative environmental impact of a structure are referred to as

Hey guys so i need to know what is _nh3+> nh4oh ~chemistry~

When the chemicals iron sulfide (fes) and hydrochloric acid (hcl) are combined, bubbles appear from the mixture. 1. does the appearance of bubbles indicate a physical or chemical change? 2. why do the bubbles indicate this change? 3. what property is this?