Question

On catalytic reduction (${{\text{H}}_2}{\text{/Pt}}$) how many alkenes will give n-butane?
A) 1
B) 2
C) 3
D) 4

Answer 1

Reduction: It is the type of redox reaction in which there is loss of electrons with respect to the transfer of electrons, and if we talk about hydrogen atoms so there is gain of hydrogens in the reduction reactions.

Complete step by step answer:
Catalytic hydrogenation is the process of addition of hydrogen to a carbon-carbon double bond to form an alkane and is also called a reduction reaction. More stable (lower energy) products are formed during hydrogenation of a double bond which is a thermodynamically favourable reaction. We can also say that the energy of the product formed is lower than the energy of the reactant; hence it is an exothermic reaction (heat is released). And the heat released during this reaction is called the heat of hydrogenation, which indicates the molecule’s stability.
An active metal catalyst is required for the reaction between hydrogen $\left( {{H_2}} \right)$ gas and an alkene (a carbon-carbon double bond). A catalyst increases the rate of reaction by lowering the activation energy required for the reaction. Apparently the catalyst does not get consumed during the reaction, it is only required for accelerating the reaction sufficiently which can be observed in a reasonable amount of time. Commonly used catalysts in alkene hydrogenation reaction are: platinum, palladium, and nickel etc. These metal catalysts provide a surface for reactants on which the reaction takes place.
The following 3 forms or butane will be formed on the catalytic reduction of alkenes:
1. but-1-ene
2. cis-but-2-ene
3. trans-but-2-ene
Therefore, 3 alkanes.

So, the correct answer is Option C.

Note: An alkene is a hydrocarbon that has a double bond character between carbon–carbon. Alkenes have many applications in the industry. They are used in the manufacturing plastics, detergents, fuels alcohol and liquors.