Question

Which of the following is correct regarding Boron and Silicon oxides?
A.Both are basic oxides
B.Both are amphoteric oxides
C.Both are acidic oxides
D.None of the above

Answer 1

Hint: An oxide is a molecule that has at least one oxygen atom and one other element (which may be a metal, non-metal, or a metalloid) in its chemical formula. Oxygen is highly reactive. They form oxides when they come in contact with metals and non-metals. Oxides are classified as:
Acidic oxide-an an oxide which when reacted with water produces an acid.
Basic oxide- an oxide which when reacted with water produces a base.
Amphoteric oxide-an an oxide which when reacted with water produces shows dual behavior as that of an acid and a base.

Complete answer:
Boron oxides are the ones that on coming in contact with water loose ${H^ + }$ions, i.e. they react with water and form an acid. To explain this reaction of diboron trioxide\[({B_2}{O_3}\;)\], which is one of the oxides of boron is shown as follows:
\[{B_2}{O_3}\; + {\text{ }}3{H_2}O\;{\text{ }} \to \;{\text{ }}2B{\left( {OH} \right)_{3\;}}\; \to {\text{ }}3{H^{1 + }}\;{\text{ }} + \;{\text{ }}\;B{O_3}{\;^{3 - }}\]
Therefore boron oxides are acidic in nature.
Silicon oxides do not react with water as they form strong double bonds with oxygen and become very stable. It is thermodynamically difficult to break up its network covalent structure. That is the reason why silicon oxides usually react with bases.
Silicon oxides are reactive towards strong bases like hot, concentrated $NaOH$ and give the product as which are silicate salts. The most common silicon oxide is silicon dioxide $Si{O_2}$. It reacts with hot concentrated $NaOH$ and forms sodium silicate which is a colorless salt and water. The reaction is as follows:
\[Si{O_2}\left( s \right){\text{ }} + {\text{ }}2NaOH\left( {aq} \right){\text{ }}N{a_2}Si{O_3}\left( {aq} \right){\text{ }} + {\text{ }}{H_2}O\left( l \right)\]
Silicon oxides are weakly acidic in nature because Silicon is too similar in electronegativity compared to that of oxygen to form ionic bonds hence do not contain oxide ions, and therefore they don’t show basic properties.

Correct option: C. Both are acidic oxides

Note:
A metal oxide is formed when it reacts with water to form an acid or reacts with a base to form a salt by donating a proton. The products formed are acidic in nature though in the case of silicon it is weakly acidic. Weakly acidic means it dissociates partially and does not ionize when in water, which is in the case of silicon oxides.