Lithium nitrate on heating gives

Fill in the blanks:
$(1)$ Among all alkali metals,.......... is a radioactive element.
$(2)$ The half-life of $^{223}Fr$ is ..........
$(3)$ Among all alkali metal ions,............ has the highest ionization enthalpy.
$(4)$ Alkali metals are identified by the ........... test.

The melting point of a mixture of $Na_2CO_3 + K_2CO_3$ is:

When a metal of group $1$ was dissolved in liquid ammonia,the following observations were obtained :
$(a)$ Blue solution was obtained initially.
$(b)$ On concentrating the solution,the blue colour changed to bronze colour.
How do you account for the blue colour of the solution? Give the name of the product formed on keeping the solution for some time.

$Na_2CO_3 \xrightarrow{\Delta} A$,'$A$' is

Match the following alloys in List-$I$ with their uses in List-$II$:

List-$I$ (Alloy)	List-$II$ (Use)
$A$. $Li-Pb$	$I$. In aircraft construction
$B$. $Be-Cu$	$II$. To make bearings for motor engines
$C$. $Mg-Al$	$III$. To make tetraethyl lead
$D$. $Na-Pb$	$IV$. To make high strength springs