Which of these is an element
a. sugar
b. salad.
c. potassium
d. water

The right option is; C. Potassium

An element is any of the simplest chemical substances that cannot be decomposed in a chemical reaction. Every element is composed of its own type of atom that has the same number of protons. The periodic table contains all the recognized elements and groups that have similar properties. Other types of elements apart from potassium include hydrogen, lithium, helium, boron, oxygen, magnesium, sulfur etc.

by cartels in other countries, shipped by air, mail, or land. i cant really see your answer choices : /

  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-