An element $(X)$ when burnt in oxygen forms a neutral oxide $(XO)$ and an acidic oxide $(XO_2)$. The element $(X)$ is:

$A$ compound $A$ is used in paints instead of salts of lead. Compound $A$ is obtained when a white compound $B$ is strongly heated. The compound $B$ is insoluble in water but dissolves in $NaOH$ solution,forming a solution of compound $C$. The compound $A$ on heating with coke gives a volatile metal $D$ and a gas $E$ which burns with a blue flame. Identify the possible species $D$ and $C$ respectively.

Which of the following orders is not correct?

What is the chief constituent of Pyrex glass?

Which of the following is a suboxide?

Which of the following does not exist?