<h2>Pressure : 11 atmosphere</h2>
Explanation:
According to gas equation P₁V₁/T₁ = P₂V₂/T₂
Where P₁ is the initial pressure , V₁ is the initial volume and T₁ is the initial temperature
P₂ is the final pressure , V₂ is the final volume and T₂ is the final temperature
Thus P₁ = 15 atmosphere , V₁ = 12 liters and T₁ = 273 + 20 = 293 K
P₂ = ? , V₂ = 8.5 liters , T₂ = 273 + 35 = 308 K
From gas equation P₂ = P₁V₁T₂/T₁V₂ = 15 x 12 x 308/ 293 x 8.5
= 22.3 atmosphere .
If the volume is doubled
The gas equation will be P₁V₁ = P₂V₂ ; because temperature is constant
Here V₂ = 2 V₁ therefore pressure P₂ = P₁/2 = 22.3/2 = 11.1 atmosphere