Fill in the blanks:
$(1)$ ......... method is used to prepare sodium carbonate.
$(2)$ Sodium carbonate exists as .........
$(3)$ Sodium chloride is commonly known as .........
$(4)$ Sodium chloride melts at ......... temperature.

(N/A) $(1)$ The Solvay process is used to prepare sodium carbonate.
$(2)$ Sodium carbonate exists as decahydrate,$(Na_2CO_3 \cdot 10H_2O)$,commonly known as washing soda.
$(3)$ Sodium chloride is commonly known as common salt or table salt.
$(4)$ Sodium chloride melts at $1081 \ K$.