Among the given group $14$ elements,the one with highest density is

What is the formula of Carborundum?

Which type of glass is used in the manufacturing of lenses and prisms?

Amphibole silicate structure has '$x$' number of corners shared per tetrahedron. The value of '$x$' is

Identify the correct statement$(s)$ from the following: $I$. The catenation property of group $14$ elements decreases from carbon to tin. $II$. Fullerene $(C_{60})$ has $20$ five-membered carbon rings and $12$ six-membered carbon rings. $III$. $SiO_2$ is soluble in conc. $NaOH$.

Identify the element whose monoxide and dioxide are acidic in nature.