What is a common characteristic of both acids and alkalis?

Acids and alkalis exhibit the common characteristic of conducting electricity in solution. This property arises from their capacity to dissociate into ions when dissolved in water. Acids release hydrogen ions (H⁺), while alkalis release hydroxide ions (OH⁻), both of which are charged particles capable of carrying electric current.

The ability of these substances to conduct electricity is a key distinguishing feature of electrolytes. This characteristic is useful in various applications, such as in battery technology and in understanding chemical reactions in ionic solutions.

Other choices, such as having a pH of 7, are not applicable to both; acids typically have a pH less than 7 and alkalis have a pH greater than 7. The notion that both react with water to generate heat is not universally correct; this is more specific to certain strong acids or alkalis rather than a general rule. Lastly, the default state of acids and alkalis varies; many are liquids or gases at room temperature rather than solids, which makes the last option inaccurate.