Which one on reaction with $NaOH$ solution gives inflammable gas?

The chloride of an element $A$ gives a neutral solution in water. In the periodic table,the element $A$ belongs to

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?

Which of the following statements is correct regarding alkali metals?

Describe two important uses of each of the following: $(i)$ caustic soda,$(ii)$ sodium carbonate,$(iii)$ quicklime.

Give reasons: Aluminium utensils should not be kept in water overnight.