Tempered steel is

Select the correct statement :-
$(a)$ $CaSO_4 \cdot 2H_2O \xrightarrow{393 \ K} CaSO_4 \cdot \frac{1}{2}H_2O + \frac{3}{2}H_2O$
$(b)$ $3Br_2 + 6NaOH \xrightarrow{\text{hot & conc.}} 5NaBr + NaBrO_3 + 3H_2O$
$(c)$ $3Mg + N_2$ $\rightarrow Mg_3N_2$ $\xrightarrow{6H_2O} 3Mg(OH)_2 + 2NH_3 \uparrow$
$(d)$ $2Be + C$ $\rightarrow Be_2C$ $\xrightarrow{4H_2O} 2Be(OH)_2 + CH_4 \uparrow$
Correct answer is :-

Match List-$I$ with List-$II$

List-$I$ Elements	List-$II$ Colour imparted to the flame
$A. K$	$I. Violet$
$B. Ca$	$II. Brick Red$
$C. Sr$	$III. Crimson Red$
$D. Ba$	$IV. Apple Green$

Choose the correct answer from the options given below:

To distinguish between $A$ and $B$,it is observed that both elements form oxides,but $B$ also forms a nitride when burnt in air. What are $A$ and $B$?

Match the elements given in Column-$I$ with the properties mentioned in Column-$II$ :

Column-$I$	Column-$II$
$A$. $Li$	$1$. Insoluble sulphate
$B$. $Na$	$2$. Strongest monoacidic base
$C$. $Ca$	$3$. Most negative $E^{\circ}$ cell value among alkali metals
$D$. $Ba$	$4$. Insoluble oxalate
	$5$. $6s^2$ outer electronic configuration

The metal that gives hydrogen gas upon treatment with both acid as well as base is