The commercial name for calcium oxide is

$Beryllium$ and $magnesium$ do not give colour to flame whereas other alkaline earth metals do so. Why?

$A$ chemistry student wants to identify the metal ion in a salt. They make a paste of the salt with concentrated $HCl$ on a clean platinum wire loop. If they take a small amount of this paste and place it in a non-luminous flame,it produces a green flame. Which metal is present?

The product obtained on fusion of $BaSO_4$ and $Na_2CO_3$ is

Which of the following statements is incorrect with reference to alkaline earth metals?

Choose the correct statements from the following:
$(I)$ In vapour phase $BeCl_2$ exists as a chlorobridged dimer.
$(II)$ $BeSO_4$ is readily soluble in water.
$(III)$ $BeO$ is completely basic in nature.
$(IV)$ $BeCO_3$ being unstable, is kept in an atmosphere of $CO_2$.
$(V)$ $BeCO_3$ is the least soluble among all the carbonates of group $2$ elements.