Which of the following metals releases hydrogen gas upon reaction with cold and dilute $HNO_3$?

The strongest reducing agent among the alkali metals is

$Na_2CO_3 \xrightarrow{\Delta} A$,'$A$' is

Sodium metal cannot be stored under

$A$ certain metal $M$ is used to prepare an antacid,which is used as a medicine for acidity. This metal accidentally catches fire,which cannot be extinguished by using $CO_2$ based extinguishers. The metal $M$ is

The alkali metals form salt-like hydrides by direct synthesis at elevated temperatures. The thermal stability of these hydrides decreases in which of the following orders?