(a) NCl5 does not exist while PCl5 does. This is correct due to N does not have vacant d-orbitals and it cannot expand its oxidation state but P has vacant d-orbitals. (b) Pb prefer to form tetravalent compound. This is wrong as to lead prefers to form bivalent compounds due to inert pair effect. (c) The three C−O bond are equal in carbonate ion. This is because the bonds are in resonance.
(d) Both‌O2+and NO are paramagnetic as they contain unpaired electrons. O2+⇒15e−(odd) paramagnetic NO⇒15e−(odd) paramagnetic Hence, only (b) option is incorrect.