Describe what happens when atoms release light?​

How is the atomic number of a nucleus changed by alpha decay

If 3 moles of a compound use 24 j of energy in a reaction, what is the a hreaction in j/mol?

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?