Which of the following metals is the most reactive?

Which metal reacts with cold water violently?

Compound $X$ and aluminium are used to join railway tracks.
$(a)$ Identify the compound $X$.
$(b)$ Name the reaction.
$(c)$ Write down its chemical reaction.

Which non-metal element is a conductor of electricity?

Two ores $A$ and $B$ were taken. On heating, ore $A$ gives $CO_2$, whereas ore $B$ gives $SO_2$. What steps will you take to convert them into metals?

Write the names and symbols of the constituents present in the following alloys:
$(a)$ Brass
$(b)$ Bronze
$(c)$ Solder