Lithium nitrate on heating gives

Explain why is sodium less reactive than potassium?

$A$ metal $X$ on heating in a stream of nitrogen gives $Y$. $Y$ on reaction with ${H_2}O$ gives a colorless gas which,when passed through a $CuSO_4$ solution,gives a blue color. What is $Y$?

When $NaOH$ crystals are left in open air,they acquire a fluid layer around each crystal because:

The correct order of the mobility of the alkali metal ions in aqueous solution is

How is $NaCl$ prepared from brine (sea water)?