Question

$2{\mathrm{SO}}_2+{\mathrm{O}}_2\to 2{\mathrm{SO}}_3+42\mathrm{KCal}.$

The above reaction is:

• A. Endothermic reaction
• B. Exothermic reaction
• C. Combination reaction
• D. Displacement reaction

Answer 1

Answer: (B), (C)

Combination reaction

The explanation for correct options: (B) and (C)

The reaction is: $2{\mathrm{SO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{SO}}_3\left(\mathrm{l}\right)+42\mathrm{KCal}.$

Option (C)-

• In a combination reaction, two or more compounds combine to form a single product.
• Sulphur dioxide and oxygen combine to form sulphur trioxide. So, it is an example of a combination reaction.

Option (B)-

• In an exothermic reaction, heat is liberated during the formation of products.
• During this reaction, there is the release of 42 KCal. So, it an also an example of an Exothermic reaction.

The explanation for the incorrect options:

Option (A)- In an Endothermic reaction heat is absorbed by the reactants, but in this reaction, heat is released. So, it is not the correct option.

Option (D)- In a displacement reaction, one substance is displaced by another element in a compound. There is no displacement of elements so it is an incorrect option.

Thus, the correct answers are options (B) and (C).