Which of the following is the strongest base?

In India,at the occasion of marriages,the fireworks used give a green flame. Which one of the following radicals may be present?

Fill in the blanks:
$(1)$ Calcium and beryllium have flame colors of ...... and ....... respectively.
$(2)$ Quantitative analysis of calcium is carried out by ........
$(3)$ Beryllium powder on combustion burns brightly in air and gives ...... and .......
$(4)$ Beryllium hydroxide on dissolving in alkali gives .......

$A$ mixture of $MgCl_2$ and $MgO$ is called

Slaked lime is used in the manufacture of

The element having atomic number $56$ belongs to