Question

all ionic compounds contain...
only transition metals.
a metal and a nonmetal.
only nonmetals.
only metals.

Explanation:

Ionic compounds are formed by the transfer of electrons from a metal to a non - metal. This creates positively charged metal ions (cations) and negatively charged non - metal ions (anions). The electrostatic attraction between these oppositely charged ions holds the compound together. For example, in sodium chloride (\(NaCl\)), sodium (a metal) donates an electron to chlorine (a non - metal).

• Option 1: Not all ionic compounds contain only transition metals. There are ionic compounds with alkali metals (e.g., \(NaCl\) with sodium, an alkali metal) and alkaline earth metals (e.g., \(MgO\) with magnesium, an alkaline earth metal).
• Option 2: This is correct as per the definition of ionic compounds (metal donates electron(s) to non - metal).
• Option 3: Compounds with only non - metals are usually covalent (sharing of electrons), not ionic.
• Option 4: Compounds with only metals are metallic (with a sea of delocalized electrons), not ionic.

Answer:

B. a metal and a nonmetal.