Ions of an element of group $1$ participate in the transmission of nerve signals and transport of sugars and amino acids into cells. This element imparts yellow colour to the flame in flame test and forms an oxide and a peroxide with oxygen. Identify the element and write chemical reaction to show the formation of its peroxide. Why does the element impart colour to the flame?

(A) The element is $Sodium$ $(Na)$.
$Na^{+}$ ions participate in the transmission of nerve signals and the transport of sugars and amino acids into cells.
The formation of its peroxide is as follows:
$2Na + O_{2} \xrightarrow{\Delta} Na_{2}O_{2}$
Reason for flame colour:
The ionisation enthalpy of $Sodium$ is low. When $Sodium$ metal or its salt is heated in a Bunsen flame,the flame energy causes the excitation of the outermost electron to a higher energy level. When this electron reverts to its initial ground state,it releases the absorbed energy as visible light. The emitted radiation corresponds to the yellow region of the spectrum,which is why $Sodium$ imparts a yellow colour to the flame.