Name the functional group of organic compounds that can be hydrogenated. With the help of suitable example explain the process of hydrogenation mentioning the conditions of the reaction and any one change in physical property with the formation of the product. Name any one natural source of organic compounds that are hydrogenated.

The functional group that can be hydrogenated is the unsaturated hydrocarbon group, specifically those containing double bonds (alkenes) or triple bonds (alkynes).

Process of Hydrogenation: Unsaturated hydrocarbons add hydrogen in the presence of catalysts such as Palladium ($Pd$) or Nickel ($Ni$) to give saturated hydrocarbons.

Example: Ethene reacts with hydrogen in the presence of a Nickel catalyst to form Ethane.

$$CH_2=CH_2 + H_2 \xrightarrow{Ni, \text{Heat}} CH_3-CH_3$$

Conditions: Presence of a catalyst (Nickel or Palladium) and heating.

Change in Physical Property: The product (saturated fat) has a higher melting point than the reactant (unsaturated oil). For example, liquid vegetable oil turns into solid vanaspati ghee.

Natural Source: Vegetable oils (like groundnut oil, sunflower oil, or cottonseed oil) are natural sources of organic compounds that undergo hydrogenation.