litre of dry air at STP expands adiabatically to a volume of 3 litres. If γ=1.40, the work done by air is: (31.4=4.6555) [Take air to be an ideal gas]

The work done by an ideal gas during an adiabatic process can be calculated using the formula:

W = P1V1((V2/V1)^(γ-1) - 1) / (γ-1)

Where:

• W is the work done
• P1 is the initial pressure
• V1 is the initial volume
• V2 is the final volume
• γ is the adiabatic index

Given in the problem:

• V1 = 1 litre
• V2 = 3 litres
• γ = 1.40

We also know that at STP (Standard Temperature and Pressure), the pressure P1 is 1 atm = 101325 Pa.

Substituting these values into the formula, we get:

W = 1013251((3/1)^(1.40-1) - 1) / (1.40-1)

Solving this equation will give us the work done by the air during this adiabatic expansion.