Is there any dative bond(molecular bond)in SO4 2- and NO3-?????if so please give the Lewis structure.?

Sulfur (S) is an element in Period 3 of the Periodic Table, and thus S atom can expand its octet (having more than 8 electrons in the outermost shell) by using the low-lying vacant 3d orbitals. As the central S atom of SO₄²⁻ ion can expand its octet, there is no dative bond in SO₄²⁻ ion.

Nitrogen (N) is an element in Period 2 of the Periodic Table, and thus N atom cannot expand its octet because there is no low-lying 3d orbitals. As the central N atom of NO₃⁻ ion cannot expand its octet, there would be dative bond in NO₃⁻ ion in order to make it obey the octet rule.

The Lewis structures of NO₃⁻ and SO₄²⁻ ions :
https://c2.staticflickr.com/8/7339/27618940205_2fdfb6db92_o.png