Question

Egg shell is made up of a chemical. In which of the two ores this chemical is present?
a.) Limestone: \[CaC{{O}_{3}}\]​, Dolomite: \[CaC{{O}_{3}}.MgC{{O}_{3}}\] ​
b.) Limestone: \[CaC{{O}_{3}}.MgC{{O}_{3}}\]​, Dolomite: \[CaC{{O}_{3}}\]
c.) Limestone: \[C{{a}_{2}}C{{O}_{3}}\], Dolomite: \[C{{a}_{2}}C{{O}_{3}}.MgC{{O}_{3}}\]
d.) None of these

Answer 1

Hint: The chemical in question is a common substance found in rocks as the minerals calcite and aragonite and is the main component of pearls and the shells of marine organisms and snails. With this information in mind, think of what this chemical could possibly be?
Complete answer:
Let us first analyse the structure of the egg’s shell before moving onto which ores the given chemical is present in.
Bumpy and grainy in texture, an eggshell is covered with as many as 17,000 tiny pores. Eggshell is made almost entirely of calcium carbonate (\[CaC{{O}_{3}}\]) crystals. It is a semipermeable membrane, which means that air and moisture can pass through its pores. The shell also has a thin outermost coating called the bloom or cuticle that helps keep out bacteria and dust.
Therefore, we now know that the chemical in question is Calcium Carbonate, let us now analyse the properties of LimeStone and Dolomite to help find a definitive answer to this question.
Remember that limestone is a carbonate sedimentary rock that is often composed of the skeletal fragments of marine organisms such as coral, foraminifera, and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (\[CaC{{O}_{3}}\]).
Also remember that dolomite is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally \[CaC{{O}_{3}}.MgC{{O}_{3}}\]. The term is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite.
Therefore, through this analysis we can conclude that the answer to this question is a).
Note:
While the bulk of eggshell is made of calcium carbonate, it is now thought that the protein matrix has an important role to play in eggshell strength. As they contain mainly calcium carbonate, bird eggshells dissolve in various acids, including the vinegar used in cooking. While dissolving, the calcium carbonate in an eggshell reacts with the acid to form carbon dioxide.