Which of the following options is correct according to the reactivity of metals?

Generally,in what forms are the elements present in the lithosphere?

$(a)$ Why does calcium start floating when added to water?
$(b)$ Most metals do not release hydrogen gas when reacting with nitric acid. Why?
$(c)$ Write the chemical equation for the reaction of iron with steam. Name the compound of iron obtained.

When a metal $X$ is treated with cold water, it gives a basic salt $Y$ with molecular formula $XOH$ (molecular mass $= 40$) and liberates a gas $Z$ which easily catches fire. Identify $X$, $Y$, and $Z$, and write the chemical reaction involved.

State three reasons for the following fact:
$(a)$ Sulphur is a non-metal.
One of the reasons must be supported with a chemical equation.

Which non-metal element is found in a gaseous state at room temperature?