The metal that is extracted from sea water is

Write the general chemical reaction that shows the dissolution of an alkali metal in liquid ammonia.

Sodium metal cannot be stored under

$A$ metal $(A)$ on heating in nitrogen gas gives compound $(B)$. $(B)$ on treatment with $H_{2}O$ gives a colourless gas which when passed through $CuSO_{4}$ solution gives a dark blue-violet coloured solution. $(A)$ and $(B)$ respectively,are

Which one of the following statements is not correct?

Important ore of $Mg$ is