The reason why alkali metals impart color to the Bunsen flame is ...

What is the gas produced in the reaction: $KO_2 + CO_2 \to ?$

Which of the following is an alkali metal?

$A$ metal $M$ reacts with $N_2$ to give a compound '$A$' $(M_3N)$. '$A$' on heating at high temperature gives back '$M$' and '$A$' on reacting with $H_2O$ gives a gas '$B$'. '$B$' turns $CuSO_4$ solution blue on passing through it. $A$ and $B$ can be

State True or False:
$(1)$ Half-life of $^{223}Fr$ is $21 \ s$.
$(2)$ $Li^{+}$ has a high hydration enthalpy and therefore its salts are usually hydrated in nature.
$(3)$ Among all the alkali metals,only $Na$ can react with nitrogen of air and form a nitride.
$(4)$ Except $LiF$,other halides of $Li$ are soluble in water.

Calcium is obtained by