Identify the cation present in chlorophyll in green plants.

$A$ solution of sodium in liquid ammonia is blue in colour due to

$A$ chloride is soluble in cold water. When it is placed on a $Pt$ wire and heated in a Bunsen flame,it does not impart any characteristic color to the flame. Which of the following cations is present?

The metal mainly used in devising photoelectric cells is:

What is the nature of cesium oxide $(Cs_2O)$?

The correct statement$(s)$ among $I$ to $III$ with respect to potassium ions that are abundant within the cell fluids is/are :
$I.$ They activate many enzymes
$II.$ They participate in the oxidation of glucose to produce $ATP$
$III.$ Along with sodium ions,they are responsible for the transmission of nerve signals