An ore of potassium is

Which of the following compounds is used as a fire extinguisher?

Which of the following statement$(s)$ is (are) correct?
$(i)$ $LiF$ is less soluble in water
$(ii)$ $NaCl$ is less ionic than $CsCl$
$(iii)$ Formation of alkali metal halide is an endothermic reaction

Liquid sodium finds use in nuclear reactors. Its function is

Hydrogen gas is evolved by the action of cold dilute $HNO_3$ on which of the following metals?

Which elements of group-$1$ and group-$2$ differ from the other elements of the same group?