Question

Oxides of boron and silicon can be reduced by _____________.

• A. reacting with limited amount of $Mg$
• B. reacting with excess amount of $Mg$
• C. Either A or B
• D. None of these

Answer 1

The correct option is A reacting with limited amount of $Mg$

Oxides of both boron and silicon are acidic and can be reduced by limited amount of $Mg$. In excess of $Mg$, boride and silicide are formed.
$B_2{O}_3+3Mg⟶3MgO+2B$
$Si{O}_2+2Mg⟶2MgO+Si$