Question

The reactions of Li, Na and K with an excess of oxygen results in the formation of X, Y and Z respectively, as major productsThe correct option(s) is/are

• A. X is an oxide, Y is a peroxide and Z is a superoxide
• B. X and Y are diamagnetic but Z is paramagnetic
• C. X is an oxide, Y is a superoxide and Z is a peroxide
• D. aqueous solutions of X, Y and Z are basic in nature

Hint:

Down the group: Li forms oxide, Na forms peroxide, K forms superoxideAlso, superoxide ions are paramagnetic

Answer 1

The Correct Option is A, B, D

Step 1: Reaction trend with oxygen.
Alkali metals react with oxygen to form different oxides depending on sizeLi forms oxide, Na forms peroxide, and K forms superoxide
\[ \text{Li} \rightarrow \text{Li}_2\text{O} \] \[ \text{Na} \rightarrow \text{Na}_2\text{O}_2 \] \[ \text{K} \rightarrow \text{KO}_2 \]

Step 2: Identify X, Y and Z.
Thus, X = Li$_2$O (oxide), Y = Na$_2$O$_2$ (peroxide), Z = KO$_2$ (superoxide

Step 3: Check statement (A).
X is oxide, Y is peroxide, Z is superoxideThus, (A) is correct

Step 4: Magnetic nature.
Li$_2$O and Na$_2$O$_2$ have all electrons paired → diamagneticKO$_2$ contains superoxide ion (O$_2^-$) which has one unpaired electron → paramagneticThus, (B) is correct

Step 5: Check statement (C).
It incorrectly assigns types of oxidesThus, (C) is incorrect

Step 6: Basic nature in water.
All three compounds react with water to produce hydroxides or basic solutionsHence, their aqueous solutions are basic

Step 7: Conclusion.
\[ \boxed{\text{(A), (B) and (D)}} \]