What two units are typically shown on thermometers?

Adilute aqueous potassium nitrate solution is

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?

What is the formula of the ionic compound composed of calcium cations and chloride anions