Which is the correct order of the first ionization potential of $N$,$O$,and $C$?

What is the decreasing order of the ionization energy for the following elements?

When first ionisation energy is plotted against the atomic number,the peaks in the curve are occupied by

Which of the following is the correct order of the first ionization energy for $B$,$C$,and $N$?

Which of the following statements is incorrect?

The successive ionization energy values for an element $X$ are given below:
$(i)$ $1^{st}$ ionization energy $= 410 \ kJ \ mol^{-1}$
$(ii)$ $2^{nd}$ ionization energy $= 820 \ kJ \ mol^{-1}$
$(iii)$ $3^{rd}$ ionization energy $= 1100 \ kJ \ mol^{-1}$
$(iv)$ $4^{th}$ ionization energy $= 1500 \ kJ \ mol^{-1}$
$(v)$ $5^{th}$ ionization energy $= 3200 \ kJ \ mol^{-1}$
Find the number of valence electrons in the atom $X$.