Final answer:
Most substances are weak electrolytes, except for strong base hydroxides of certain elements. Strong bases are hydroxides of alkali metals and heavy alkaline earth metals, which dissociate almost completely into ions in water. Weak bases are usually ionic compounds except for ammonia.
Step-by-step explanation:
Most substances that are weak electrolytes except the strong base hydroxides (strong electrolytes) of Li, Na, K, Rb, Ca, Sr, and Ba.
Strong bases are hydroxides of alkali metals (LiOH, NaOH, KOH, RbOH, and CSOH) and hydroxides of heavy alkaline earth metals (Ca(OH)2, Sr(OH)2, and Ba(OH)2), which are strong electrolytes. They dissociate almost 100% into ions when dissolved in water.
Weak bases are usually ionic compounds except ammonia (NH3), which is a covalent compound. Ionic compounds are strong electrolytes because they dissociate into ions almost 100% upon dissolution in water.