Which is true of hydroxide ions?

A. They dissociate to form protons.

B. They contain two hydrogen atoms.

C. They have a negative charge.

D. They are not found in pure water.

C

Explanation:

hydroxide ion contains one oxygen and one hydrogen atoms. valency of H is +1 and that of O is -2 .When both of the atoms combine the valency of H got satisfied but that of O is not fully satisfied which becomes the reason for negative charge on hydroxide ion

d. cellulose and starch