What is the electronic configuration of sulphur?

State whether the following statement is true or false:
At ordinary temperature,the surfaces of metals such as magnesium,aluminium,zinc,lead,etc.,are covered with a thin layer of oxide which prevents the metal from further oxidation.

$(a)$ 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.

An element forms an oxide $A_{2}O_{3}$ which is acidic in nature. Identify $A$ as a metal or non-metal.

Which acid is formed when sulfur dioxide reacts with water?

Which alloy consists of copper and tin?