An ylide is a molecule that can be described as a:

a. carbocation bound to a carbon radical.
b. carbocation bound to a positively charged heteroatom.
c. carbanion bound to a positively charged heteroatom.
d. carbanion bound to a negatively charged heteroatom.
e. carbocation bound to a diazonium ion.

Option c. carbanion bound to a positively charged heteroatom.

Explanation:

A ylide is a molecule containing a negatively charged usually a carbnion atom directly bonded to a positively charged heteroatom in which both atom have complete octet congratulations.

the answer is definitely c.

  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-