Sulphur Dioxide - P-Block Elements Questions and Answers

This set of Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “P-Block Elements – Sulphur Dioxide”.

1. What is the chemical formula of sulfur dioxide?
a) SO₂
b) SO₆
c) SO₃
d) S₂O₃
View Answer

Answer: a
Explanation: Sulfur dioxide is the most commonly known oxide of sulfur, which occurs naturally and can be prepared in labs too. Industrially, it is an essential gas to produce a variety of chemicals involving SO₂ as the chief component. For e.g. contact process for producing sulfuric acid.

2. Which of the following causes acid rain?
a) Carbonic acid
b) Sulfurous acid
c) CFCs
d) Hydrogen chloride
View Answer

Answer: b
Explanation: Sulfurous acid causes acid rain. When sulfur is burned or sulfur compounds are released into the atmosphere, it rises up in the atmosphere to mix with water vapor to form sulfurous acid, H₂SO₃ or it reacts with more oxygen to form sulfur trioxide which forms sulfuric acid, H₂SO₄ on mixing with vapor and precipitating as acid rain.

3. Which of the following is not a property of sulfur dioxide?
a) Colorless
b) Bent molecule
c) Odorless
d) Polar molecule
View Answer

Answer: c
Explanation: Sulfur dioxide has a very nasty, pungent and sharp smell. It is a choking gas, released when sulfur compounds are burned in excess oxygen. It is a colorless gas and bears a bent shape with polarity due to the electronegativity of the oxygen atom. The structural formula is ^–O – S = O.

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4. Which reagent is used in qualitative testing for presence of sulfur dioxide?
a) Sodium Chloride
b) Iron (II) sulfate
c) Vanadium (V) oxide
d) Potassium permanganate
View Answer

Answer: d
Explanation: Acidified potassium permanganate is used to test the presence of SO₂. A filter paper or cotton wool dipped in acidified KMnO₄ is held over the gas, the former decolorizes, confirming the presence of gas.

5. What is the primary component of food preservative E220?
a) Sulfur dioxide
b) Sodium benzoate
c) Sodium glutamate
d) Potassium sorbate
View Answer

Answer: a
Explanation: Sulfur dioxide is coded as preservative E220 when used in Europe. It is known for its antimicrobial properties and ability to prevent oxidation. It is responsible for maintaining the colorful appearance and prevents rotting.

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6. Which of the following is a suffocating gas produced during incomplete combustion of fuels?
a) Sulfur dioxide
b) Carbon monoxide
c) Carbon dioxide
d) Nitrogen dioxide
View Answer

Answer: b
Explanation: Incomplete combustion of fuels results in the release of carbon monoxide due to limited amount of oxygen burning the fuel. Carbon monoxide is an asphyxiant, meaning it tends to block oxygen supply to cell and cause death due to suffocation.

7. Which of the following is not a criterion for air pollutants monitored by U.S – EPA?
a) Sulfur dioxide
b) Ozone
c) Mercury
d) Lead
View Answer

Answer: c
Explanation: Mercury is not included in the list of criteria for monitoring air pollutants by U.S. – EPA. The criteria air pollutants are carbon monoxide, lead, ozone, sulfur dioxide, nitrogen oxides, and particulate matter

8. Which compound is used as a reducing bleach for papers
a) Sulfur trioxide
b) Sulfur
c) Sulfur dioxide
d) Hydrogen sulfide
View Answer

Answer: c
Explanation: In presence of water, SO₂ is able to decolorize substances. Specifically, it is used as a reducing bleach for papers although the bleaching effect does not last very long. It is an essential process to remove lignin, a natural element that causes paper to turn brown.

9. If a aryl diazonium salt is treated with sulfur dioxide, what product forms?
a) Benzene sulfonic acid
b) Aryl Sulfonyl Chloride
c) Thiophenol
d) Thiophene
View Answer

Answer: b
Explanation: When aryl diazonium salts are treated with sulfur dioxide in presence of CuCl and acetic acid, it forms aryl sulfonyl chloride Diazonium salts are highly unstable intermediates due to the N≡N⁺ bond.

10. Before the invention of CFCs, which of the compounds was used extensively as a refrigerant?
a) Ammonia
b) Diethyl ether
c) Sulfur dioxide
d) Ice
View Answer

Answer: c
Explanation: Sulfur dioxide was used as a refrigerant before CFCs. This is due to its characteristic features bearing high heat of evaporation and ability to be easily condensed.

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