Which process is used to convert sulphide ores into oxides by heating them in the presence of excess air?

Explain the following:
$(a)$ The reactivity of $Al$ decreases if it is dipped in $HNO_3$.
$(b)$ Carbon cannot reduce the oxides of $Na$ or $Mg$.

Food cans are coated with tin and not with zinc because:

$A$ non-metal $X$ exists in two different forms $Y$ and $Z$. $Y$ is the hardest natural substance, whereas $Z$ is a good conductor of electricity. Identify $X$, $Y$ and $Z$.

Which alloy is used for making aircraft parts?

Generally,metals are solid in nature. Which one of the following metals is found in liquid state at room temperature?