Which statements about propadiene (allene), $\mathrm{CH}{}_2=\mathrm{C}=\mathrm{CH}{}_2$, are correct?

The central carbon has two sigma bonds and no lone pair ($sp$) while the terminal carbons are $s{p}^2$. The molecule has 4 C-H plus 2 C-C sigma bonds (6) and 2 pi bonds. The two pi bonds use perpendicular p orbitals of the central carbon, so the two $\mathrm{CH}{}_2$ planes are perpendicular and the molecule is not planar.