What is meant by a skeletal chemical equation?

Translate the following statements into chemical equations and then balance them.
$(a)$ Hydrogen gas combines with nitrogen to form ammonia.
$(b)$ Hydrogen sulphide gas burns in air to give water and sulphur dioxide.

In which of the following chemical equations,the abbreviations represent the correct states of the reactants and products involved at reaction temperature?

Write word equations and then balanced chemical equations for the reactions taking place when:
$(a)$ Dilute sulphuric acid reacts with aluminium powder.
$(b)$ Dilute hydrochloric acid reacts with iron filings.

Explain the "Oxidation" in terms of gain or loss of oxygen with two examples.

Balance the following chemical equation:
$Fe(s) + H_2O(g) \rightarrow Fe_3O_4(s) + H_2(g)$