What type of reaction is   zn + 2hcl > zncl2 + h2 combustion, synthesis, decomposition, single displacement, double displacement, or acid-base neutralization

In which situation can a mixture always be called a solution

Take a look at this dandelion. the yellow flower on the right is pollinated and the seeds on the left are transported by

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?