Different what of an element have different numbers of neutrons ions isotopes compounds molecules

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?

Which of the following is not an assumption that scientists must make about the natural world? a. regularity b. causality c. predictability d. plausibility

If maltose undergoes hydrolysis what subunits does it results to?