Which of the following oxides is acidic in nature?

Give a brief account of the production of cement and write its properties and uses.

$[SiF_6]^{2-}$ is known whereas $[SiCl_6]^{2-}$ is not. Give possible reasons.

$A$ tetravalent element forms monoxide and dioxide with oxygen. When air is passed over the heated element $(1273 \ K)$,producer gas is obtained. The monoxide of the element is a powerful reducing agent and reduces ferric oxide to iron. Identify the element and write the formulas of its monoxide and dioxide. Write chemical equations for the formation of producer gas and the reduction of ferric oxide with the monoxide.

Among the following options,the element with the highest density and lowest boiling point is

Which of the following anions is present in the chain structure of silicates?