Which pair of elements can form multiple bonds with itself and oxygen?

The $C-C$ bond length is maximum in?

Buckminsterfullerene contains the following $X$ number of six-membered and $Y$ number of five-membered rings. What is the value of $X$ and $Y$?

Which of the following is an amphoteric oxide?

Assertion $(A)$: Graphite is used as a dry lubricant in machines which run at high temperatures.
Reason $(R)$: The layers of graphite slip one over the other when pressure is applied.
The correct option among the following is:

Which of the following halides does not hydrolyse at room temperature?