Which daughter element is produced from the beta decay of 19 Ba?

Explanation for basic character?

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 can be done to make a solid solute dissolve faster in a liquid solvent?