WHAT IS THE COLOUR CHANGE WHEN WE ADD PHENOLPTHALEIN TO ACIDS AND BASES?

When we add phenolpthalein to acids it becomes colourless. When we add phenolpthalein to bases, the clour turns to MAGENTA. 

WHAT HAPPENS WHEN CARBONATES REACT WITH ACIDS?

Well it is mostly possible with metallic carbonates. When carbonates react with acids they give salt, water and carbon dioxide is released. Remember acids have replaceable hydrogen atoms.
So :
Metallic carbonates + acids = salt + water + carbon dioxide