You start at 10 atm and -40 Celsius you move 20 atm and 70 Celsius what kind of change has happened

Explanation:

It is a physical change .

If we start from 10 atm of pressure and - 40 celsius of temperature to 20 atm of pressure and 70 celsius of temperature , it is a change in which pressure increases and temperature also increases that means heat is added up to the gas . If we cool the gas we can retrieve its earlier pressure and temperature .

So it is  a physical change . In physical change , we can retrieve the old position by simple means.