Which amongst the following is incorrect statement?

1. Bond orders calculated via MOT are correct.2. ${\text{C}}_2$ (12 electrons): $\sigma 1s^2{\sigma }^{\ast }1s^2\sigma 2s^2{\sigma }^{\ast }2s^2\pi 2p_x^2\pi 2p_y^2$. Four electrons in $\pi$ orbitals. Correct.3. ${\text{H}}_2^{+}$ has $(2-1)=1$ electron. Correct.4. Incorrect statement: ${\text{O}}_2^{+}$ has 15 electrons. The configuration ends in ${\pi }^{\ast }2p_x^1{\pi }^{\ast }2p_y^0$. It has one unpaired electron and is therefore paramagnetic, not diamagnetic.