Question

Match the List-I containing some compounds with their characteristics in List-II and choose the correct option.

List-I	List-II
(P) K$_3$CrO$_8$	(1) Different oxidation state of central atom
(Q) Pb$_3$O$_4$	(2) Maximum number of peroxide bond among given compound and central atom is not in maximum oxidation state
(R) Br$_3$O$_8$	(3) Minimum number of peroxide bond among given compound with maximum oxidation state of central atom
(S) H$_2$S$_2$O$_8$	(4) Difference in oxidation state of central atom in compound is 2
	(5) Different oxidation state of oxygen

• A. P-2, Q-1, R-4, S-3
• B. P-2, Q-4, R-1, S-5
• C. P-2, Q-1, R-1, S-3
• D. P-2, Q-4, R-1, S-3

Answer 1

Answer: (D)

P-2, Q-4, R-1, S-3

Answer 2

Let's analyze each compound and match it with its characteristics:

(P) K$_3$CrO$_8$:

• This is potassium perchromate, containing the [Cr(O$_2$)$_4$]$^{3-}$ ion.
• Oxidation state of Cr = +5. The maximum oxidation state for Cr is +6.
• There are 4 peroxide ($O_2^{2-}$) groups, meaning 4 peroxide bonds (O-O).
• Characteristic (2) states: "Maximum number of peroxide bond among given compound and central atom is not in maximum oxidation state". K$_3$CrO$_8$ has the maximum number of peroxide bonds (4) among the given compounds, and Cr is in +5 oxidation state (not maximum). Thus, (P) matches (2).

(Q) Pb$_3$O$_4$:

• This is lead tetroxide, a mixed oxide represented as 2PbO·PbO$_2$.
• Two Pb atoms are in the +2 oxidation state, and one Pb atom is in the +4 oxidation state.
• Characteristic (1) states: "Different oxidation state of central atom". This applies to Pb$_3$O$_4$.
• Characteristic (4) states: "Difference in oxidation state of central atom in compound is 2". The oxidation states are +2 and +4, and the difference is 4 - 2 = 2. This also applies to Pb$_3$O$_4$.
• Since (4) is a more specific description of the difference in oxidation states than (1), and to ensure unique matching if possible, we consider (4) as the primary match for Pb$_3$O$_4$.

(R) Br$_3$O$_8$:

• This is tribromine octoxide. Its structure can be considered as O$_3$Br-O-BrO$_2$-O-BrO$_3$.
• The oxidation states of the three Br atoms are +6, +4, and +6.
• Characteristic (1) states: "Different oxidation state of central atom". This applies to Br$_3$O$_8$.
• Characteristic (4) states: "Difference in oxidation state of central atom in compound is 2". The oxidation states are +4 and +6, and the difference is 6 - 4 = 2. This also applies to Br$_3$O$_8$.
• If (Q) is matched with (4), then (R) should be matched with (1), as both have different oxidation states for the central atom, but the difference is 2 for both. However, in a typical matching question, if one compound has a specific difference (like 2), and another has a general "different oxidation state", the specific one is often paired with the specific characteristic. Given the options, it's likely that Q is paired with 4 and R with 1, or vice-versa. Let's assume Q-4, R-1 based on option 4.

(S) H$_2$S$_2$O$_8$:

• This is peroxydisulfuric acid, with the structure HO$_3$S-O-O-SO$_3$H.
• Oxidation state of S = +6, which is the maximum oxidation state for sulfur.
• There is one peroxide bond (O-O), where oxygen atoms have an oxidation state of -1. The other oxygen atoms have an oxidation state of -2.
• Characteristic (3) states: "Minimum number of peroxide bond among given compound with maximum oxidation state of central atom". H$_2$S$_2$O$_8$ has 1 peroxide bond (minimum among those with peroxide bonds) and its central atom (S) is in its maximum oxidation state (+6). Thus, (S) matches (3).
• Characteristic (5) states: "Different oxidation state of oxygen". In H$_2$S$_2$O$_8$, oxygen exists in -1 (peroxide) and -2 states. Thus, (S) also matches (5).

Considering the likely intent of a matching question to have unique primary matches:

• (P) $\rightarrow$ (2) (Unique for max peroxide bonds and not max OS)
• (S) $\rightarrow$ (3) (Unique for min peroxide bond and max OS)

Now we are left with (Q) and (R) to be matched with (1) and (4).

• (Q) Pb$_3$O$_4$: Pb(+2, +4). Difference is 2. Matches (1) and (4).
• (R) Br$_3$O$_8$: Br(+4, +6). Difference is 2. Matches (1) and (4).

If we choose (4) for (Q) (specific difference), then (1) is left for (R) (general difference). This gives: P-2, Q-4, R-1, S-3.

Let's check option 4: P-2, Q-4, R-1, S-3. This pairing is consistent with our analysis. (P) $\rightarrow$ (2) (Q) $\rightarrow$ (4) (R) $\rightarrow$ (1) (S) $\rightarrow$ (3)

This leaves characteristic (5) unused, which is common in some matching questions where not all options might be used or where multiple characteristics apply but only one is chosen for the match.