Answer: The precipitate formed is 
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 or precipitated form are represented by (s) after their chemical formulas.
A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.
The balanced chemical equation is:

Answer:
It decreases
Explanation:
As one moves from left to right on the periodic table, the radius of atoms reduces due to the nuclear pull.
- The size of an atom estimated by the atomic radius is taken as half of the internuclear distance between the two covalently bonded atoms of non-metallic elements.
- Across a period, atomic radius decreases progressively from left to right.
- This is due to the increasing nuclear charge without attendant increase in the number of electronic shell.
carbon, hydrogen, nitrogen, and oxygen. the number infront is how many of each element there are, they are increasing and decreasing