Resonance and formal charge

All of the bonds in $\ce{CO3^2-}$ are identical in length and strength.

The bonds in $\ce{CCl4}$ are more polar than the bonds in $\ce{CH4}$.

Both of the bonds in $\ce{BeH2}$ have a bond order of $1$1.

$\ce{NF3}$ contains three single bonds between nitrogen and fluorine.