Question

The weakest reducing agent among the following is:
A. hydrogen gas
B. coke
C. carbon monoxide gas
D. aluminum metal

Answer 1

Hint: An element having higher standard electrode potential is considered to be a good oxidizing agent. On the other hand, an element having lowest standard electrode potential is considered to be a good reducing agent.

Complete step by step answer:
We know that the standard reduction potential value of coke, carbon monoxide gas and aluminium all have a negative value. The element hydrogen as a positive value of standard reduction potential, that is, $0$.
As we know that to be a good oxidizing agent, that is a weak reducing agent, the value of the standard electrode potential must be a high value. Therefore, we can say that hydrogen having a value of 0 standard reduction potential will act as a weak reducing agent in comparison to coke, carbon monoxide and aluminum metal. Hence, out of the given four options. A is the correct answer and options B, C and D are incorrect.

So, the correct answer is Option A .

Additional Information:
Hydrogen gas is one of the most abundant gas available to us. It has many utilities. Hydrogen gas is used in the nitrogen fixation in the Haber ammonia process, it is used in the oils and fats hydrogenation, it is used as an important component in the rocket fuel, in welding etc.

Note:
In a redox reaction, there exists one reducing agent and one oxidizing agent. The reducing agent is the one that loses an electron and the oxidizing agent is marked by the gaining of an electron.