Which of the following reaction is a Double Displacement reaction?
(i) 2Mg + O2 > 2MgO
(ii) CaCO3 > CaO + CO2
(iii) CuSO4 + Fe > FeSO4 + Cu
(iv) BaCl2 + Na2SO4 > BaSO4 + 2NaCl
1
(i) and (ii)
2
only (iv)
3
(iii) and (iv)
4
only (iii)