# A gas does 50 J of work as it expands adiabatically. Is the change in thermal energy of this gas 50 J, 0 J, or -50 J?

From the $1$ st law of thermodynamics we know,
$\partial Q = \partial U + \partial W$
For,adiabatic process,change in total energy=$\partial Q = 0$ (by definition)
And,change in internal energy = $\partial U = - \partial W = - 50 J$