Question

Two moles of a gas, initially at pressure P, volume V and temperature T, expand at constant pressure until the volume doubles. Then the gas is adiabatically cooled to its initial temperature wherein it's volume becomes 4√2V and pressure P/4√2. The adiabatic constant is
a) 5/2
b) 5/3
c) 7/5
d) 9/7​

Answer 1

Answer:

the answer is b one 5/3 because

Explanation:

y

= Constant

and y=

3

5

for a monoatomic gas

P

1

v

1

5/3

=P

2

v

2

5/3

As, it is a compression process, v

2

<v

1

and v

2

<v

1

and so, P

2

>P

1, the gas is given heat

′

Q

′

at constant v

2

.

By first law of thermodynamics, dq=dv+dw

⇒Q=

2

t

nR△T+0

and Pv=nRT ⇒Q=

2

t

nR

nR

v△P

−

2

t

v△P

⇒△PV=△nRT ⇒

fv

2

2Q

=p

3

−p

2

△Pv=△nRT ⇒p

3

=p