Question

 Define the following terms of gain or loss of hydrogen with one example each:

A. Oxidation

B. Reduction

Answer 1

Hint: Oxidation is defined as the process in which there is gain in oxygen and loss of electrons. Reduction is defined as the process in which there is loss of oxygen and the gain in electrons. Both processes are the exact opposite of each other.

Complete answer:

Oxidation is the process in which there is gain of oxygen or loss of an electron by an element. It is when an element combines with oxygen. One example of such a reaction is that magnesium in its solid or reacts with oxygen in its gaseous form to form a solid magnesium oxide. Oxidation is also defined as the loss of electrons by the element. Oxidation state of the element increases and it loses electrons.

Reduction is the process in which there is loss of oxygen by an element. It is when an element loses oxygen. It can also be considered as the gain of electrons as not all the compounds that get reduced have an oxygen so there happens again in electrons. One example of one such reaction is when magnesium oxide in its solid form combines with carbon in its solid form or coke to form magnesium in its solid form and carbon monoxide

Now the question asks to explain the following in terms of hydrogen, now for that lets take the reaction

${H_2}S + C{l_2} \to S + 2HCl$

Now what happens in the reaction is that the sulphur loses hydrogen and the chlorine atom gains hydrogen. Now which of them is oxidation and which one reduces, now simply the sulphur loses its electrons and goes into zero oxidation state and the chlorine gains the electrons and forms its ion so as to form a compound with hydrogen and therefore gain hydrogen.

Now we can say that 

A. loss of electron in sulphur or loss of Hydrogen is called oxidation 

B. gain of electrons in chlorine or the gain of hydrogen is defined as reduction.

Note:
Now the oxidation process can also be defined as the gain of oxygen atom as in that case it loses electrons and the reduction process in terms of oxygen can be defined as the loss of oxygen and hence gaining electrons in the process therefore called reduction.