Which of the following carbonates undergoes decomposition upon heating?

How would you explain the following observations?
$(i)$ $BeO$ is almost insoluble but $BeSO_4$ is soluble in water,
$(ii)$ $BaO$ is soluble but $BaSO_4$ is insoluble in water,
$(iii)$ $LiI$ is more soluble than $KI$ in ethanol.

Which of the following statement$(s)$ is/are incorrect?

Match the following:

Metal	Uses
$1. \text{Be}$	$c. \text{To prepare windows of X-rays}$
$2. \text{Ca}$	$d. \text{To remove air from vacuumized tubes}$
$3. \text{Mg}$	$a. \text{To prepare Grignard reagent}$

The property of the alkaline earth metals that increases with their atomic number is

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