Which metal does not react with cold water but evolves $H_2$ gas when reacted with steam?

In the presence of air,washing soda loses $9$ molecules of water to form a monohydrate: $Na_2CO_3 \cdot 10H_2O \xrightarrow{\text{In open air}} Na_2CO_3 \cdot H_2O + 9H_2O$. This process is known as:

Which of the properties of alkali metals is not listed correctly?

Which of the following ions has a lower enthalpy of hydration than the $Mg^{2+}$ ion?

What is caused by an excess of $Na^{+}$ ions in the human body?

Which of the following exhibits the maximum photoelectric effect?