chemistry : class12 Structure of Trithionic Acid : Structures of oxoacids of sulphur : p-Block Elements MCQ Questions and Answers
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Structure of Trithionic Acid
MCQ questions and answers.
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MCQ Questions
1. Which structural formula correctly represents trithionic acid, H2S3O6?
A.
HO-S(=O)2-S-S-S(=O)2-OH
B.
HO-S(=O)2-S-S(=O)-OH
C.
HO-S(=O)-S(=O)-S(=O)-OH
D.
HO-S(=O)2-S(=O)-S-OH
Correct Answer:
HO-S(=O)2-S-S-S(=O)2-OH
Explanation:
Trithionic acid has the structure HO3S-S-S-SO3H, equivalently HO-S(=O)2-S-S-S(=O)2-OH. It contains two terminal sulfonic-acid groups joined by an S-S-S chain.
2. In the structure HO-S(=O)2-S-S-S(=O)2-OH of trithionic acid, how many sulfur-sulfur single bonds are present?
A.
One
B.
Two
C.
Three
D.
Four
Correct Answer:
Two
Explanation:
The three sulfur atoms form a continuous S-S-S chain. Therefore, the structure contains two S-S single bonds.
3. What is the oxidation state of each terminal sulfur atom in trithionic acid, represented as HO-S(=O)2-S-S-S(=O)2-OH?
A.
+2
B.
+4
C.
+5
D.
+6
Correct Answer:
+5
Explanation:
Each terminal sulfur is bonded to two doubly bonded oxygen atoms, one hydroxyl oxygen, and one sulfur atom. Assigning oxygen as -2 and hydrogen as +1 gives an oxidation state of +5 for each terminal sulfur.
4. What is the oxidation state of the middle sulfur atom in the structural formula of trithionic acid?
A.
-2
B.
0
C.
+2
D.
+4
Correct Answer:
0
Explanation:
The middle sulfur is bonded only to two sulfur atoms. Since sulfur-sulfur bonds do not create an oxidation-state difference between identical atoms, its oxidation state is 0.
5. Which combination correctly gives the oxidation states of the three sulfur atoms in trithionic acid, ordered from one terminal sulfur to the other?
A.
+5, 0, +5
B.
+4, +2, +4
C.
+6, -2, +6
D.
+5, +1, +5
Correct Answer:
+5, 0, +5
Explanation:
The two terminal sulfur atoms belong to -SO3H groups and each has oxidation state +5, while the sulfur atom between them is connected only through S-S bonds and has oxidation state 0.
6. How many S-O bonds and S-S bonds are present in one molecule of trithionic acid?
A.
Six S-O bonds and two S-S bonds
B.
Six S-O bonds and three S-S bonds
C.
Four S-O bonds and two S-S bonds
D.
Four S-O bonds and three S-S bonds
Correct Answer:
Six S-O bonds and two S-S bonds
Explanation:
Each terminal sulfur has three S-O bonds: two S=O bonds and one S-OH bond. Thus there are six S-O bonds altogether, and the three-sulfur chain contributes two S-S bonds.
7. Which statement about the hydroxyl groups in trithionic acid is structurally correct?
A.
Both hydroxyl groups are attached to the middle sulfur atom.
B.
One hydroxyl group is attached to the middle sulfur and one to a terminal sulfur.
C.
Each hydroxyl group is attached to a terminal sulfur atom.
D.
The hydroxyl groups are attached directly to the S-S bond.
Correct Answer:
Each hydroxyl group is attached to a terminal sulfur atom.
Explanation:
The structure is HO-S(=O)2-S-S-S(=O)2-OH. Therefore, each end sulfur carries one S-OH group, while the middle sulfur carries no oxygen or hydrogen.
8. Which structural feature distinguishes trithionic acid from sulfuric acid when their oxoacid frameworks are compared?
A.
Trithionic acid contains an S-S-S chain between two terminal sulfur(V) centers.
B.
Trithionic acid contains three S-OH groups around one sulfur center.
C.
Trithionic acid contains only one sulfur atom bonded to oxygen.
D.
Trithionic acid contains an S-O-S linkage instead of sulfur-sulfur linkages.
Correct Answer:
Trithionic acid contains an S-S-S chain between two terminal sulfur(V) centers.
Explanation:
Trithionic acid has the polythionate arrangement HO3S-S-S-SO3H, in which two terminal sulfur(V) groups are connected through sulfur-sulfur bonds. This chain is the defining structural feature.
9. In the Lewis-type structural representation of trithionic acid, what is the total number of sulfur-oxygen double bonds?
A.
Two
B.
Three
C.
Four
D.
Six
Correct Answer:
Four
Explanation:
Each terminal sulfur has two S=O bonds. Since trithionic acid has two terminal sulfur atoms, the total number of sulfur-oxygen double bonds is four.
10. The average oxidation state of sulfur in trithionic acid, H2S3O6, is best explained by which value and structural distribution?
A.
0; all three sulfur atoms are equivalent and unoxidized
B.
+2; the sulfur atoms have oxidation states +2, +2, and +2
C.
+10/3; the sulfur atoms have oxidation states +5, 0, and +5
D.
+5; all three sulfur atoms are present as terminal sulfonic sulfur
Correct Answer:
+10/3; the sulfur atoms have oxidation states +5, 0, and +5
Explanation:
The total oxidation number of sulfur is +10 because 2(+1) + 3x + 6(-2) = 0. The average is therefore +10/3, arising from the structural distribution +5, 0, and +5 rather than equivalent sulfur atoms.
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