The number of sigma $(\sigma)$ and pi $(\pi)$ bonds in peroxodisulphuric acid are, respectively:

The correct statement among the following is:

Who first provided an explanation for the formation of chemical bonds in terms of electrons?

Which of the following statement$(s)$ is/are correct? [$T$ for True and $F$ for False$]$
$(a)$ Hybrid orbitals form stronger bonds than pure atomic orbitals.
$(b)$ Canonical structures have a difference in the arrangement of atoms $w.r.t.$ each other.
$(c)$ Any symmetrical molecule always contains the same bond angle.
$(d)$ $VSEPR$ theory can explain the square planar geometry of $XeF_4$.

If compound $MX_4$ is non-polar and has no lone pair at the central atom,then the bond angle $\angle XMX$ in the compound may be:

The correct order of increasing bond length of $C - H, C - O, C - C$ and $C=C$ is