Answer:
C: Carbon monoxide - Acidic nature
Step-by-step explanation:
A) Beryllium is not soluble in water but yet it reacts with an acid and a base. Therefore, since it exhibits both basic and acidic nature, we say it is Amphoteric in nature. Thus it is correct
B)potassium super oxide has the formula KO2. It reacts with acid to form salt called potassium chloride. Thus, it is basic in nature.
C) Carbon monoxide does not react with acids or bases. Thus, it doesn't show either an acidic or basic property and we say it is a neutral oxide. This option is incorrect
D) Bismuth oxide is a basic oxide because it displays properties of a base. This options is correct