Question

Hardening of oil is done by:
A. dehydrogenation
B. hydrogenation
C. dehydrohalogenation
D. dehydration

Answer 1

Hint: This process is accomplished by the addition of hydrogen to convert double and triple bonds to a saturated compound. Saturated compounds are those having only a single chain across the carbon network. Various transition metals are used as catalysts in this process for the conversion of unsaturated compounds to saturated compounds.

Complete step by step answer:
Hardening of oil is the other name of hydrogenation.
The process of the formation of the saturated compound from the unsaturated compounds by adding hydrogen is called hydrogenation.
Vegetable oil, containing double and triple bonds when treated with hydrogen in the presence of Nickel catalyst, is converted into vegetable ghee, a saturated compound.
$vegetable\text{ oil + }{{H}_{2\text{ }}}\xrightarrow{Ni\text{ }catalyst}\text{ }vegetable\text{ }ghee$
Vegetable oils are liquid at room temperature. It is required to hydrogenate them to make them user-friendly, that is to make them more solid or ‘spreadable’.
It will help in using them in the manufacture of other foodstuffs like cakes, biscuits and so on.
So, the correct option is B.

Additional information:
It is essential to know that trans fats increase the level of ‘bad’ cholesterol, whereas saturated fats increase the level of ‘good’ cholesterol.

Note: Partial hydrogenation of oils forms trans fatty acids (TFAs) while complete hydrogenation of oils forms cis fatty acids which are more dangerous for our health. Cis addition means the addition of the same group on one side of double or triple bonds and trans addition is the addition of the same group on either side of double or triple bonds.