Question

Which of the following elements has the same oxidation state in all of its compounds?

• A. Carbon
• B. Oxygen
• C. Fluorine
• D. Hydrogen

Answer 1

The correct option is C

Fluorine

The explanation of the correct option:

C) Fluorine

• The oxidation state of an atom is defined as the total number of electrons it gains or loses to form a chemical bond with another atom which, in together form a compound. It is a hypothetical number given to an atom.
• Fluorine exists in only one oxidation state which it $-1$
• Fluorine is the most electronegative atom in the periodic table and it needs only one electron to fulfill its octet state hence it only has one oxidation state.

The explanation for incorrect options:

A) Carbon

• Carbon exists in more than one oxidation state because it has the valency of $4$, and the oxidation states vary accordingly.
• The oxidation states that Carbon shows are: From $-4\mathrm{to}+4$and hence its oxidation state changes according to a compound.

B) Oxygen

• Oxygen exists in different oxidation states with different compounds. For example, it usually exists in a $-2$state but when exists peroxide, it is in a $-1$state
• The oxidation states in which Oxygen exists are: From $-2\mathrm{to}+2$and hence its oxidation state changes according to a compound.

D) Hydrogen

• The oxidation state of hydrogen is usually $+1$in most cases except in that of $\mathrm{NaH}$where it exists in a $-1$state.
• Here, the sodium atom is more electropositive than the hydrogen atom, and therefore it shows the oxidation state is negative.
• Hence, hydrogen's oxidation state varies with the type of compound it forms.

Therefore, option C) fluorine is correct.