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Stoichiometry
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Simultaneous doubling of the absolute temperature of a gas and reduction of its pressure to half, will result in __________ in the volume of the gas.

Answer & Solution
Correct Answer: Option D
According to the ideal gas law, for a fixed amount of gas:

PV = nRT

Since the amount of gas (n) and gas constant (R) stay constant, the relationship between volume, temperature, and pressure is:

V ∝ T/P

You are doubling the absolute temperature (T₂ = 2T₁), and at the same time reducing the pressure to half (P₂ = 0.5P₁).

So, the new volume compared to the original volume will be:

V₂/V₁ = (T₂/T₁) * (P₁/P₂)

Substituting the values gives:

V₂/V₁ = (2T₁/T₁) * (P₁/0.5P₁)

V₂/V₁ = 2 * 2 = 4

Therefore, the volume of the gas will experience a four fold increase, not just doubling.
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1 Comment
Atanu Chatterjee
Atanu Chatterjee 1 year ago
We use the Ideal Gas Law:

𝑃
𝑉
=
𝑛
𝑅
𝑇
PV=nRT
Let’s analyze what happens when:

Temperature is doubled →
𝑇
2
=
2
𝑇
1
T
2
​
=2T
1
​


Pressure is halved →
𝑃
2
=
1
2
𝑃
1
P
2
​
=
2
1
​
P
1
​


We assume amount of gas (n) and gas constant (R) remain constant.

Step-by-step:
From ideal gas law:

𝑃
1
𝑉
1
𝑇
1
=
𝑃
2
𝑉
2
𝑇
2
T
1
​

P
1
​
V
1
​

​
=
T
2
​

P
2
​
V
2
​

​

Substitute the changes:

𝑃
1
𝑉
1
𝑇
1
=
(
𝑃
1
/
2
)
𝑉
2
2
𝑇
1
T
1
​

P
1
​
V
1
​

​
=
2T
1
​

(P
1
​
/2)V
2
​

​

Multiply both sides to eliminate denominators:

𝑃
1
𝑉
1
=
𝑃
1
2
⋅
𝑉
2
2
=
𝑃
1
𝑉
2
4
P
1
​
V
1
​
=
2
P
1
​

​
⋅
2
V
2
​

​
=
4
P
1
​
V
2
​

​

Now solve for
𝑉
2
V
2
​
:

𝑃
1
𝑉
1
=
𝑃
1
𝑉
2
4
⇒
𝑉
2
=
4
𝑉
1
P
1
​
V
1
​
=
4
P
1
​
V
2
​

​
⇒V
2
​
=4V
1
​

✅ Correct answer: D. Four fold increase