Which of these statements is not true?

$\displaystyle \mathrm{NO}^{+}$is not isoelectronic with $\displaystyle \mathrm{O}_2$

B is always covalent in its compounds

In aqueous solution, the $\displaystyle \mathrm{Tl}^{+}$ion is much more stable than Tl (III)

$\displaystyle \mathrm{LiAlH}_4$ is a versatile reducing agent in organic synthesis.