Question

The metal present in the eggshell belongs to:
A. ${2^{nd}}period$
B. ${3^{rd}}period$
C. ${4^{th}}period$
D. ${5^{th}}period$

Answer 1

Eggshell is made up entirely of the crystals of calcium carbonate ($CaC{O_3}$). It is a type of semipermeable membrane, which means that air and moisture can be passed through its pores. The shell also has a thin outermost coating known to be the cuticle that protects from the bacteria and dust. Nanoparticles of calcium carbonate are arranged into ordered crystals by proteins, eventually forming the calcite mineral that makes up the cell. The shell is not completely solid rather it is made up of thousands of tiny pores.

Complete step by step answer:
-The main metal present in an eggshell is calcium.
-It has an atomic number of twenty and a symbol Ca.
-Its electronic configuration is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^2}$. So we can say that the valence electrons are present in the fourth shell.
-It belongs to the group of alkaline earth metals and the fourth period of the periodic table.
-Eggshells are roughly $40\%$calcium.
-Half an eggshell may provide enough calcium to meet the daily requirements of adults.
-Eggshells are also commonly used as a calcium supplement as they are mainly calcium carbonate which corresponds to about of the shell.

Hence, option C is the correct answer. $94\%$.

Note:
-In addition to calcium and protein, small amounts of other minerals including strontium, fluoride, magnesium, and selenium are also present on eggshells. Just like calcium these minerals play a vital role in bone health.
-Eggshells can be used as a calcium and mineral-rich additive to feed birds.
-They can also be used as a soil additive for houseplants as they add minerals and help keep the soil loose and aerated.
-The main element of eggshells calcium helps plants to build their cell walls and is an important component in the bones and teeth of animals. It also helps the animals to move their muscles.