Due to low ionization energy,alkali metals are...

The dark red colour of bombs in fireworks is due to the presence of:

Sodium peroxide is used to purify the air in submarines and confined spaces because

Fill in the blanks:
$(1)$ Lithium on reaction with nitrogen present in air is denoted by .....
$(2)$ Potassium gives ...... colour in oxidizing flame.
$(3)$ ....... and ........ metals are used in photoelectric cells.
$(4)$ When alkali metal dissolves in ammonia,it produces a blue-coloured solution. This colour is due to .......

Which among the following is used as a source of oxygen in submarines in emergency breathing apparatus?

Which of the following does not participate in the Solvay process for the manufacture of $Na_2CO_3$?