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Which of the following catalysts is used during the hydrogenation of oil?
(A) \[Fe\]
(B) \[Ni\]
(C) \[Pt\]
(D) \[Mo\]

Answer
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Hint: We need to know what catalyst is and what hydrogenation is. Catalyst is a substance which accelerates or speeds up the rate of a chemical reaction without itself being consumed or undergoing any change in its composition or mass and the process is known as catalysis.
We have to know that hydrogenation is the process of chemical reaction where hydrogen atoms bind to the double bond of a compound, facilitating its conversion to a single bond, in the presence of a catalyst.

Complete step by step answer:
We have to remember that the process of hydrogenation of oils is a chemical reaction between unsaturated liquid oil and atomic hydrogen in the presence of a metal catalyst.
Finely divided metals, such as platinum, palladium and nickel, are among the most widely used hydrogenation catalysts but mostly nickel is used widely due to its low cost.
Oils are adsorbed on the surface of the catalyst along with some of the hydrogen
Hydrogens shift from the metal surface to the carbons of the double bonds present in the oils and the resulting saturated hydrocarbon which is more weakly adsorbed, leaves the catalyst surface.
The nickel catalyst is then removed from the hydrogenated fat by filtration.
For example, when the vegetable ghee is formed by converting vegetable oil using nickel catalyst.
${\text{Vegetable oi}}{{\text{l}}_{\left( l \right)}} + {H_{2\left( g \right)}}\xrightarrow{{Ni\left( s \right)}}{\text{Vegetable ghe}}{{\text{e}}_{\left( s \right)}}$
Thus, it is clear that the catalyst widely used in the hydrogenation of oils is Nickel.
Hence the correct option is option (B).

Additional information:
Usually, a very small quantity of the catalyst is required. There are mainly 3 types of catalysis based on the physical nature of catalysts:
Homogenous catalysis: The catalysts and reactants are in the same phase.
Heterogeneous catalysis: The catalysts and reactants are in different phases.
Enzymatic catalysis: The catalyst in an enzyme (macromolecules made of amino-acids).
They do so by interacting with the reactants and products and reducing the activation energy (activation energy is the energy that must be provided to compounds to result in a chemical reaction) or by changing the reaction mechanism.
We must remember that hydrogenation is commonly used during the manufacturing of food products where unsaturated fats and oil are converted to saturated fats and oils.

Note:
 It must be noted that platinum and palladium can also be used but they are avoided due to their high costs. Although the overall hydrogenation reaction is exothermic, a high activation energy prevents it from taking place under normal conditions. This restriction may be overcome by the use of a catalyst. Also, \[Ni\] used as a catalyst in hydrogenation of oil is an example of heterogeneous catalysis.