Answer: 
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
The balanced chemical equation when when aqueous solutions of chromium(III) sulfate and calcium nitrate are combined is:

The International System of Units is the current international standard metric system and is also the system most widely used around the world.
By using it for a long time lol.
not sure.. you should eat poptarts
Answer:
An external stimuli is a stimulus that comes from outside an organism and causes a reaction.An internal stimuli is a stimulus that comes from inside an organism.