A. RbOH is a base because its pH is greater than 7. This statement is correct and points at the compound being a base because an Alkali always has a pH between 7 and 14. Starting from 7 which is a neutral compound neither acidic nor alkaline, the higher the pH value, the stronger the compound is an alkali or a base. The strongest pH compounds are those that have the pH value of 14 and the weakest alkalis are those the pH value of which is closer to 7. None of the other options fit this criteria.
C. Niche overlap is small and the carrying capacities are similar.
Explanation:
The Lotka-Volterra model is used to predicts if coexistence of two species is possible .The Lotka–Volterra models show that coexistence is more likely if niche overlap is small and the carrying capacities are similar.
A and D are incorrect as these are bonds either between metals and nonmetals or non metals and non metals. C is incorrect as this term is a joining of sugar molecules.