Which type of oxide is $CO_{2}$?

In the presence of which catalyst is vegetable ghee prepared from vegetable oil?

Name one metal and one non-metal that exist in liquid state at room temperature. Also,name two metals having a melting point less than $310\ K$ $(37\ ^\circ C)$.

Which metal is used in thermometers?

$(a)$ 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.

Non-metals form two types of oxides. Choose these two types from the following oxides:
$SO_2, NO_2, CO, H_2O, N_2O$