Which of the following decreases on going gradually from $Be$ to $Ba$ in the periodic table?

Among the alkaline earth metals ($Be$,$Mg$,$Ca$,and $Sr$) of group $IIA$,which one forms an ionic chloride?

Gypsum is added to clinker during cement manufacture to:

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

Heating compound $(A)$ produces a colorless gas and a residue $(B)$ which dissolves in water. Passing excess $CO_2$ gas through the aqueous solution of $(B)$ yields compound $(C)$,which is obtained in solid state. Gently heating compound $(C)$ gives back the white solid $(A)$. What is compound $(A)$?

An alkaline earth metal $M$ readily forms water-soluble sulphate and water-insoluble hydroxide. Its oxide $MO$ is very stable to heat and does not have rock-salt structure. $M$ is :-