Which of the following gives a green color in the flame test?

Assertion $(A)$: $MgO$, $CaO$, $SrO$, and $BaO$ are insoluble in water.
Reason $(R)$: In aqueous medium, the basic strength of $MgO$, $CaO$, $SrO$, and $BaO$ increases with an increase in the atomic number of the metal.
The correct option among the following is:

Given below are two statements:
Statement $I$: Both $CaCl_2 \cdot 6H_2O$ and $MgCl_2 \cdot 8H_2O$ undergo dehydration on heating.
Statement $II$: $BeO$ is amphoteric whereas the oxides of other elements in the same group are acidic.
In the light of the above statements,choose the correct answer from the options given below:

The solubility of sulfates in water decreases down the group for $Be$ to $Ba$. The correct order is $BeSO_4 > MgSO_4 > CaSO_4 > SrSO_4 > BaSO_4$. The reason for this is:

What is the difference in the number of water molecules between gypsum and plaster of Paris?

The alkaline earth metal that imparts apple green colour to the Bunsen flame when introduced in it in the form of its chloride is