Which of the following groups of elements have chemical properties that are most similar?

Assertion $(A)$: $Be$ and $Mg$ do not impart any colour to the flame.
Reason $(R)$: The electrons in them are too strongly bound to get excited by the energy of the flame.
The correct option among the following is:

The ionic carbide is

Choose the correct statement$(s)$:
$A.$ Beryllium oxide is purely acidic in nature.
$B.$ Beryllium carbonate is kept in the atmosphere of $CO_2$.
$C.$ Beryllium sulphate is readily soluble in water.
$D.$ Beryllium shows anomalous behavior.
Choose the correct answer from the options given below:

Which of the following compounds is used for the preparation of quicklime?

Water is periodically sprinkled on cement plasters during curing. What does this help in?