Which of the following is an alloy?

What type of compounds are formed when reactive metals like sodium and potassium react with dihydrogen?

From amongst the metals sodium,calcium,aluminium,copper and magnesium,name the metal:
$(i)$ which reacts with water only on boiling,and
$(ii)$ another which does not react even with steam.

During the electrolytic refining of zinc,it gets :

The electronic configurations of three elements $X$, $Y$, and $Z$ are $X: {2, 8}$, $Y: {2, 8, 7}$, and $Z: {2, 8, 2}$. Which of the following is correct?

An element $A$ is soft and can be cut with a knife. It is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following: