Question

# Metal oxides are ………………… in nature.A.basicB.acidicC.neutralD.none of these

Hint: Metal oxides are the oxides of metal like $N{a_2}O$ and $MgO$ etc. They consist of a metal cation and an oxide anion. Normally metals form three different types of oxides which are oxides, peroxide and superoxides.

Oxides are a class of compounds where an oxygen atom is bonded to another atom. Metals can donate their electrons in valence shells for pairing up with oxygen atoms leading to such compounds. The metals combine with oxide ion ${O^{2 - }}$ to give ionic oxides.
Metal oxides react with water vigorously to generate different compounds. This accounts for the acid-base character of metal oxide. In general ionic metal oxides react with water producing compounds which contain hydroxide ions. Thus the reaction with water results in forming a basic solution.
Let us consider the metal oxides of alkali and alkaline earth metals which are purely ionic metal oxides.
The Alkali metals are presented in group I elements in periodic tables. They exhibit a valency of one as they contain only one electron in their outermost shell. They metal oxides formed of alkali metal have the formula ${M_2}O$, where ${M^ + }$ the metal cation and ${O^{2 - }}$ is the oxide anion. The reaction of alkali metal with water gives hydroxides which are basic. For example, sodium oxide $N{a_2}O$ reacts with water to give $NaOH$.
$N{a_2}O + {H_2}O \to 2NaOH$
The alkaline earth metals are group II elements in periodic tables. They exhibit valency of two as they contain two electrons in the outermost shell. The metal oxides formed of alkaline metal have the formula $MO$, where ${M^{2 + }}$ is the metal cation and ${O^{2 - }}$ is the oxide anion. The reaction of alkaline metal with water gives hydroxides which are basic. For example, magnesium oxide $MgO$ reacts with water to give $Mg{\left( {OH} \right)_2}$.
$MgO + {H_2}O \to Mg{(OH)_2}$
Another reason which indicates the basic nature of metal oxides is their ability to react with acids. Metal oxides react inorganic acids like $HCl$ to give salts and water.
${M_2}O + 2HCl \to 2MCl + {H_2}O$
Thus the nature of metal oxides is basic rather than acidic or neutral.

Note: Nonmetals or metalloids can give oxides which are acidic in nature. They react with water giving an acidic solution. For example $C{O_2}$, $S{O_2}$ reacts with water to produce ${H_2}C{O_3}$ and ${H_2}S{O_4}$. These compounds are acidic known as carbonic acid and sulphuric acid.