What is the symbol for an atom containing 20 protons and 22 neutrons?

Chemistry worksheet - i am not sure what they are asking for exactly?

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?

How many moles in .5g of sodium bromide?