Which of the following is a mixed oxide?

An oxide of an element is a gas and dissolves in water to give an acidic solution. The element belongs to:

Which of the following gases present in the air blackens the surface painted with white lead?

An inorganic compound $(A)$ made of the two most occurring elements in the earth's crust,having a polymeric tetrahedral network structure. With carbon,compound $(A)$ produces a poisonous gas $(B)$ which is the most stable diatomic molecule. Compounds $(A)$ and $(B)$ are:

The number of six-membered carbon rings and five-membered carbon rings present in Buckminsterfullerene are $x$ and $y$ respectively. The sum of $x$ and $y$ is:

For a good quality cement,the ratio of silica to alumina is found to be