When a Gram positive bacterial culture is too old, it is possible that the Gram stain reaction will not be accurate. This is because the cell wall of an old bacterial cell has become weakened. Therefore, the cell wall becomes “leaky” and is more likely to no longer be able to retain the primary dye during the Gram stain procedure.

option c is the correct answer.

chert is a sedimentary rock composed of microcrystalline or cryptocrystalline silica. with this little bit of information, you can come to the conclusion that your answer is c.  

explanation:

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.