Describe the preparation and properties of $CO_2$.

Preparation:
$1$. By complete combustion of carbon and carbonaceous fuels in excess of air: $C(s) + O_2(g) \rightarrow CO_2(g)$.
$2$. By the action of dilute hydrochloric acid on metal carbonates: $CaCO_3(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + CO_2(g) + H_2O(l)$.
Properties:
$1$. It is a colourless and odourless gas.
$2$. It is slightly soluble in water,forming carbonic acid: $H_2O(l) + CO_2(g) \rightleftharpoons H_2CO_3(aq)$.
$3$. It is acidic in nature and reacts with alkalis to form carbonates: $2NaOH(aq) + CO_2(g) \rightarrow Na_2CO_3(aq) + H_2O(l)$.