is kerosene a pure substance

No, Kerosene is not a pure substance. We know that a pure substance is one that cannot be separated into different constituents by physical or chemical processes. A pure substance is one that contains particles of only one type of a substance.

Kerosene is a mixture of hydrocarbons; the chemical composition depends on its source, but it usually consists of about 10 different hydrocarbons, each containing 10 to 16 carbon atoms per molecule. The main constituents are saturated straight-chain and branched-chain paraffins, as well as ring-shaped cycloparaffins (also known as naphthenes). The components in the mixture could be separated.