Question

Silicon is an important constituent of
A. Rocks
B. Amalgams
C. Chlorophyll
D. Hemoglobin

Answer 1

Silicon is a metal with atomic number 14. It is a hard crystalline solid with a blue-grey metallic coat. Silicon element is not found freely in nature rather it exists as silicates. So from the given options, find which of them consists of silicates and that will be our answer.

Complete answer: We are given to find for which of the given options silicon is an important constituent.
We know that silicon is a brittle crystalline metal with atomic number 14 and represented by the symbol “Si”. Silicon is not found free in nature that is why it occurs mainly as its oxide which is a silicate.
Amalgam is a mixture of a metal with mercury. Silver amalgam which is a mixture of silver and mercury is used as a dental filling to fill the teeth. So we can say that Silicon is not present in an amalgam, rather mercury is present in it.
Chlorophyll is present in plants which absorb sunlight. Chlorophyll molecule contains a central magnesium atom which is surrounded by a porphyrin (nitrogen) ring. So we can say that Silicon is not present in chlorophyll.
Hemoglobin is a protein and the reason for the blood to be in red color. In the hemoglobin protein, a component called the heme group contains iron as the central metal atom. So silicon is not present in hemoglobin too.
Rocks contain silicate minerals and compounds that include silicon oxide in their lattice. The proportion of Silica in rocks is a determining factor for their names and properties. So now we can say that Silicon is an important constituent in rocks.

Hence, the correct option is Option A.

Note: Silicon dioxide is also known as silica. Do not confuse between silicon and silica as silicon is an element and silica is a compound. Silicates not only contain silicon but also are made up of other elements too like oxygen, aluminum etc.