What consists of a pair of centrioles and pericentriolar material?

Centrosome - a dense network of small protein fibers near the nucleus of the cell, containing a pair of centrioles and pericentriolar material.

pericentriolar material is the part of a cell

Microtubules.

A material that exists of only silicon and oxygen is called "Silica". Normally when found on it's own, silica is called Quartz. However, most volcanic minerals have some amount of silica in them.

Class A combustibles are generally considered to be ordinary items such as wood, paper, trash. Class A fires are extinguishable with a Class A fire extinguisher -(Water)