Assertion : $s-$Block elements do not occur free in nature.
Reason : $s-$Block elements are highly electropositive in nature.

Identify the reactions in which,upon heating,a diatomic gas is evolved,leaving behind a metallic residue.
$(A)$ $2NaN_{3(s)} \xrightarrow{\Delta} 2Na_{(s)} + 3N_{2(g)}$
$(B)$ $Ni(CO)_{4(g)} \xrightarrow{250^{\circ}C} Ni_{(s)} + 4CO_{(g)}$
$(C)$ $2KClO_{3(s)} \xrightarrow{\Delta} 2KCl_{(s)} + 3O_{2(g)}$
$(D)$ $2HgO_{(s)} \xrightarrow{\Delta} 2Hg_{(l)} + O_{2(g)}$
$(E)$ $NH_{4}NO_{2(s)} \xrightarrow{\Delta} N_{2(g)} + 2H_{2}O_{(g)}$

Compare the alkali metals and alkaline earth metals with respect to $(i)$ ionization enthalpy,$(ii)$ basicity of oxides,and $(iii)$ solubility of hydroxides.

Choose the correct order.

Tempered steel is

Which of the following electronic configurations belongs to $s-$block elements?