Explain why silicon tetrachloride is hydrolyzed but carbon tetrachloride is not hydrolysed.

CCl₄ is not hydrolysed by water because carbon has no d-orbitals and hence cannot expand its coordination number beyond 4. However, silicon atom of silicon tetrachloride has energetically suitable vacant d-orbitals. Thus, it can accept a lone pair of electrons from oxygen atom of a water molecule. Therefore, silicon atom can expand its coordination number beyond four. Due to this reason SiCl₄ is hydrolysed.

In this reaction, all the four chlorine atoms of SiCl₄ are replaced by four OH groups.