(Q014) Silicates a. are classified on the basis of what kind of metals they contain. b. form through the evaporation of water. c. are a large category of minerals that includes the common minerals calcite and dolomite. d. have the silicon-oxygen tetrahedron as their structural unit.

d. have the silicon-oxygen tetrahedron as their structural unit.

Explanation:

Silicates are anions that have both Oxygen and Silicon as the basis of their structure. These two form a tetrahedron type structure that enable them to be useful for a whole lot of things.

Silicates are very abundant on Earth as they comprise around 95% of the Earth's crust as well as the upper mantle which explains why they are mostly found in igneous rocks.

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms