Chile saltpetre is

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

Which of the following metals produces hydrogen gas on reacting with cold dilute nitric acid?

What is the chemical formula of Indian saltpeter?

Which among the following elements develops noble gas configuration in $+1$ state?

$A$ 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