Which of the following is an amphoteric oxide?

Which of the following is not a monomer for a high molecular mass silicone polymer?

The stability of dihalides of $Si, Ge, Sn$ and $Pb$ increases in the order:

$PbO_2$ reacts with concentrated $HNO_3$. The gas evolved is:

An inorganic compound $(A)$ made of the two most abundant elements in the Earth's crust is used in building construction. When $(A)$ reacts with carbon,it forms a poisonous gas $(B)$,which is a very stable diatomic molecule. Identify compounds $(A)$ and $(B)$.

$CO + NaOH \to $