Question

The oxidation number of potassium in \( K_2O \), \( K_2O_2 \) and \( KO_2 \) respectively are:

• A. \( +1, +2, +4 \)
• B. \( +1, +2, +1 \)
• C. \( +1, +1, +1 \)
• D. \( +2, +1, +1 \)

Hint:

Alkali metals like potassium almost always show \( +1 \) oxidation state, even in oxides, peroxides, and superoxides.

Answer 1

The Correct Option is C

Step 1: Recall oxidation state of potassium.
Potassium is an alkali metal and belongs to Group 1.
It generally shows a fixed oxidation state of \( +1 \) in its compounds.

Step 2: Oxidation number in \( K_2O \).
In \( K_2O \), oxygen has oxidation number \( -2 \).
Let oxidation number of potassium be \( x \).
\[ 2x + (-2) = 0 \]
\[ 2x = 2 \]
\[ x = +1 \]

Step 3: Oxidation number in \( K_2O_2 \).
In \( K_2O_2 \), oxygen is present as peroxide ion \( O_2^{2-} \).
The total charge on peroxide ion is \( -2 \).
Let oxidation number of potassium be \( x \).
\[ 2x + (-2) = 0 \]
\[ 2x = 2 \]
\[ x = +1 \]

Step 4: Oxidation number in \( KO_2 \).
In \( KO_2 \), oxygen is present as superoxide ion \( O_2^- \).
The total charge on superoxide ion is \( -1 \).
Let oxidation number of potassium be \( x \).
\[ x + (-1) = 0 \]
\[ x = +1 \]

Step 5: Conclusion.
Thus, the oxidation number of potassium in \( K_2O \), \( K_2O_2 \), and \( KO_2 \) is \( +1 \) in each case.
Therefore:
\[ \boxed{+1,\; +1,\; +1} \]