Which of the following factors is responsible for $Li$ being the strongest reducing agent among alkali metals?

Which of the following alloys are correctly matched with their uses?
$(i)$ $Li-Mg$ armour plates
$(ii)$ $Cu-Be$ high strength springs
$(iii)$ $Mg-Al$ aircraft construction

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.

Zinc reacts with caustic soda to form........

Which of the following,when heated with a solution of caustic soda,produces a combustible gas?

Which of the following metals liberate hydrogen gas on reaction with dilute $H_2SO_4$?