Which of the following colours is developed when alkali metal is dissolved in liquid ammonia?

The chloride of an element $A$ gives a neutral solution in water. In the periodic table,the element $A$ belongs to

The correct variation of the following properties of group $1$ elements $(M)$ ($Li$ to $Cs$) is:

Sodium is heated in air at $300^{\circ} C$ to form $X$. $X$ absorbs $CO_2$ and forms $Na_2CO_3$ and $Y$. Which of the following is $Y$?

Which one of the following will react most vigorously with water?

Metallic magnesium is prepared by