$NO_2$ is not obtained on heating:

Which of the following statements about $Na_2O_2$ is not correct?

Alkali metals in each period have

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R:$
Assertion $A:$ Metallic sodium dissolves in liquid ammonia giving a deep blue solution,which is paramagnetic.
Reason $R:$ The deep blue solution is due to the formation of amide.
In the light of the above statements,choose the correct answer from the options given below:

The oxide of potassium that does not exist is

What are the by-products in the Solvay process for the production of $Na_2CO_3$?