Question

Ex Match Type

Column-I Oxy acid (A) Pyrosulphurous acid (B) Peroxydisulphuric acid (C) dithionic acid (D) Pyrosulphuric acid

Column-II (P) Basicity = 2 (Q) S-S linkage is present (R) difference in oxidation state of sulphur atoms is zero (S) S-O-S linkage is present (T) atleast one sulphur atom have +3 oxidation state

Answer 1

A - P, Q, T; B - P, R; C - P, Q, R; D - P, R, S

Answer 2

The solution involves determining the structure, basicity, oxidation states of sulphur, and the presence of specific linkages (S-S, S-O-S) for each given oxyacid of sulphur.

(A) Pyrosulphurous acid ($H_2S_2O_5$). The structure is $H-O-S(=O)-S(=O_2)-O-H$.

Basicity: It has two acidic hydrogens bonded to oxygen, so basicity = 2. (P)

Linkages: It contains an S-S bond. (Q) It does not contain an S-O-S linkage. (S is not matched)

Oxidation states of Sulphur: In $H-O-S(=O)-S(=O_2)-O-H$, the S atom bonded to one =O and one -OH has an oxidation state of +3 ($+1 + x + (-2) + (-1) = 0 \implies x = +2$. No, this is incorrect calculation. Let's use the formula method for each S. For the S with one =O, one -OH, one S: $x_1 + 1(-2) + 1(-1) + 1(0) + 1(+1) = 0 \implies x_1 -2 -1 +1 = 0 \implies x_1 = +2$. Still incorrect. Let's use counting bonds method. For S(=O)(-OH)(-S): 1 S-S bond (0), 1 S=O bond (+2), 1 S-OH bond (+1). Sum = +3. For the S(=O$_2$)(-OH)(-S): 1 S-S bond (0), 2 S=O bonds (+4), 1 S-OH bond (+1). Sum = +5. So the oxidation states are +3 and +5.

Difference in oxidation state: $5 - 3 = 2$, which is not zero. (R is not matched)

At least one sulphur atom has +3 oxidation state: Yes, one S is +3. (T)

Matches for (A): (P), (Q), (T).

(B) Peroxydisulphuric acid ($H_2S_2O_8$). The structure is $H-O-S(=O_2)-O-O-S(=O_2)-O-H$.

Basicity: It has two acidic hydrogens bonded to oxygen, so basicity = 2. (P)

Linkages: It contains an O-O peroxide linkage. It does not contain S-S (Q is not matched) or S-O-S linkage (S is not matched).

Oxidation states of Sulphur: In $H_2S_2O_8$, the average oxidation state is $2(1) + 2x + 8(-2) = 0 \implies 2 + 2x - 16 = 0 \implies 2x = 14 \implies x = +7$. This is incorrect because of the peroxide link. Using the structure: Each S is bonded to one -OH (+1), two =O (+4), and one -O-O- (+1). Total oxidation state = +1 + 4 + 1 = +6. So both S atoms are in +6 oxidation state.

Difference in oxidation state: $6 - 6 = 0$. (R)

At least one sulphur atom has +3 oxidation state: No. (T is not matched)

Matches for (B): (P), (R).

(C) Dithionic acid ($H_2S_2O_6$). The structure is $H-O-S(=O_2)-S(=O_2)-O-H$.

Basicity: It has two acidic hydrogens bonded to oxygen, so basicity = 2. (P)

Linkages: It contains an S-S bond. (Q) It does not contain an S-O-S linkage. (S is not matched)

Oxidation states of Sulphur: In $H_2S_2O_6$, the average oxidation state is $2(1) + 2x + 6(-2) = 0 \implies 2 + 2x - 12 = 0 \implies 2x = 10 \implies x = +5$. Using the structure: Each S is bonded to one -OH (+1), two =O (+4), and one S (0). Total oxidation state = +1 + 4 + 0 = +5. So both S atoms are in +5 oxidation state.

Difference in oxidation state: $5 - 5 = 0$. (R)

At least one sulphur atom has +3 oxidation state: No. (T is not matched)

Matches for (C): (P), (Q), (R).

(D) Pyrosulphuric acid ($H_2S_2O_7$). The structure is $H-O-S(=O_2)-O-S(=O_2)-O-H$.

Basicity: It has two acidic hydrogens bonded to oxygen, so basicity = 2. (P)

Linkages: It contains an S-O-S linkage. (S) It does not contain an S-S bond. (Q is not matched)

Oxidation states of Sulphur: In $H_2S_2O_7$, the average oxidation state is $2(1) + 2x + 7(-2) = 0 \implies 2 + 2x - 14 = 0 \implies 2x = 12 \implies x = +6$. Using the structure: Each S is bonded to one -OH (+1), two =O (+4), and one -O-S (+1). Total oxidation state = +1 + 4 + 1 = +6. So both S atoms are in +6 oxidation state.

Difference in oxidation state: $6 - 6 = 0$. (R)

At least one sulphur atom has +3 oxidation state: No. (T is not matched)

Matches for (D): (P), (R), (S).

Summary of matches:

(A) Pyrosulphurous acid ($H_2S_2O_5$): (P), (Q), (T)

(B) Peroxydisulphuric acid ($H_2S_2O_8$): (P), (R)

(C) Dithionic acid ($H_2S_2O_6$): (P), (Q), (R)

(D) Pyrosulphuric acid ($H_2S_2O_7$): (P), (R), (S)

Let's recheck the structure and oxidation states of Pyrosulphurous acid ($H_2S_2O_5$). While $H-O-S(=O)-S(=O_2)-O-H$ with oxidation states +3 and +5 is widely accepted, some older texts or alternative definitions might consider an S-O-S structure $H-O-S(=O)-O-S(=O)-O-H$ where both S are +3. If this structure is used for $H_2S_2O_5$:

Basicity = 2 (P)

S-S linkage = No (Q is not matched)

Difference in oxidation state = $3-3=0$ (R)

S-O-S linkage = Yes (S)

At least one S is +3 = Yes (T)

Matches for (A) with S-O-S structure: (P), (R), (S), (T).

Comparing the matches derived from both structures for (A) with the options provided in typical match-the-column questions, it is more likely that the question intends the S-S structure for $H_2S_2O_5$ because option (Q) (S-S linkage) is a distinct structural feature. If the S-O-S structure was intended, (A) would match (R) and (S), which are also matched by (D). The S-S linkage in (A) and (C) helps differentiate them.

Let's stick with the S-S structure for (A).

(A) Pyrosulphurous acid ($H_2S_2O_5$): (P), (Q), (T)

(B) Peroxydisulphuric acid ($H_2S_2O_8$): (P), (R)

(C) Dithionic acid ($H_2S_2O_6$): (P), (Q), (R)

(D) Pyrosulphuric acid ($H_2S_2O_7$): (P), (R), (S)

Final matches:

A - P, Q, T

B - P, R

C - P, Q, R

D - P, R, S