Answer:
a) The final pressure is 1.68 atm.
b) The work done by the gas is 305.3 J.
Explanation:
a) The final pressure of an isothermal expansion is given by:

Where:
: is the initial pressure = 5.79 atm
: is the final pressure =?
: is the initial volume = 420 cm³
: is the final volume = 1450 cm³
n: is the number of moles of the gas
R: is the gas constant
Hence, the final pressure is 1.68 atm.
b) The work done by the isothermal expansion is:

Therefore, the work done by the gas is 305.3 J.
I hope it helps you!
Answer:
126000 J
Explanation:
Applying,
Q = cm(t₂-t₁).................. Equation 1
Where Q = Amount of heat, c = specifc heat capacity of water, m = mass of water, t₁ = Initial temperature, t₂ = Final temperature.
From the question,
Given: m = 2 kg, t₁ = 25°C, t₂ = 40°C
Constant: c = 4200 J/kg.°C
Substitute these value into equation 1
Q = 2×4200(40-25)
Q = 2×4200×15
Q = 126000 J