The number of water molecules in gypsum,dead burnt plaster and plaster of paris,respectively are:

Which of the following elements does not react with water?

Which of the following oxides is most acidic in nature?

Which of the following alkaline earth metals shows some properties similar to aluminium?

Portland cement contains '$X$' to enhance the setting time. What is '$X$'?

Predict the feasibility of the given reactions in aqueous solution:
$(i)$ $Be(OH)_2 + 2 OH^{-} \longrightarrow [Be(OH)_4]^{2-}$
$(ii)$ $Be(OH)_2 + 2 H^{+} \longrightarrow Be^{2+} + 2 H_2O$