Question

$4$ moles each of $S O_{2}$ and $O_{2}$ gases are allowed to react to form $SO_{3}$ in a closed vessel. At equilibrium $25 \%$ of $O_{2}$ is used up. The total number of moles of all the gases present at equilibrium is

• A. 6.5
• B. 7
• C. 8
• D. 2

Answer 1

Answer: (A)

6.5

Answer 2

Total number of moles at equilibrium

$=4(1-0.25)+4(1-0.25)+0.5$
$=4-1+4-1+0.5=6.5$