Which of the following is an acidic oxide?

On heating,compound $(A)$ gives a gas $(B)$ which is a constituent of air. This gas,when treated with $H_{2}$ in the presence of a catalyst,gives another gas $(C)$ which is basic in nature. $(A)$ should not be:

The stable bivalency of $Pb$ and trivalency of $Bi$ is

$Pb + \text{Dil. } HNO_3 \xrightarrow{\text{Warm}} P + Q\uparrow + H_2O$
Incorrect statement for $Q$ is

Which of the following oxides of nitrogen is the anhydride of nitrous acid?

The number of pentagons in $C_{60}$ and trigons (triangles) in white phosphorus,respectively,are