Which of the following are forms that chemical hazards can be in?

This question is about electrolysis. metal spoons can be coated with silver. this is called electroplating. suggest one reason why spoons are electroplated?

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?

Chris is about to do an experiment to measure the density of water at several temperatures. his teacher has him prepare and sign a safety contract before beginning the experiment. which term is mostlikely part of the safety contract