In a lab experiment, students combined the solution of potassium iodide with lead (II) nitrate and the following reaction took place. Students also observed that a solid yellow precipitate of lead (11) iodide is
produced.
KI + Pb(NO3)2 → KNO3 + Pbl2
(yellow precipitate)

the answer is the

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.

gold is my favorite solid.