Which of the following statement is incorrect when a system consisting of ideal gas undergoes change of state?

In an isochoric process, $\mathrm{\Delta }{S}_{\mathrm{syst}}=n{C}_v\ln \left(\frac{T_2}{T_1}\right)$

In reversible change, $\mathrm{\Delta }{S}_{\text{univ }}=0$

In an adiabatic process always, $\mathrm{\Delta }{S}_{\text{syst }}=0$

In an irreversible change, $\mathrm{\Delta }{S}_{\text{univ }}\ne 0$