Question

The pressure of a monatomic ideal gas is doubled, while the volume is cut in half. By what factor is the internal energy of the gas multiplied? (a) 1/4 (b) 1/2 (c) 1 (d) 2 (e) 4

Answer 1

Answer:

option C

multiplication factor n = 1 when volume change to half and pressure become double

Explanation:

we know by Ideal Gas law:

P1V1 = nRT1

P2V2 = nRT2

according to the question

pressure is doubled and volume is reduced to half  

so we have

new pressure = 2*P1

new volume = V1/2

hence,

(2P1) * (V1/2) = nRT2

P1V1 = nRT2

we have now

nRT1 = nRT2

we get

T1 = T2

thus no change in temperature

we know that internal energy is given as

internal energy = nCvT,

since temperature is directly proportional to internal energy and since temperature remains constant therefore internal energy remains constant

So there is no change in internal energy

thus, multiplication factor n = 1 when volume change to half and pressure change to double