The process of industrial manufacturing of sodium carbonate is known as

Which of the following gives a green colour to flame?

Which of the following reactions does not liberate a gaseous product?

Which among the following elements has only one electron in the valence shell?

The alkali metals dissolve in liquid $NH_3$. Which of the following statements is correct?

Assertion $A$: Alkali metal elements impart characteristic colors to the flame in a flame test.
Reason $R$: They have very low ionization enthalpy.