The true statement is :
1
∇ × (∇ϕ) = \(\overline{0}\)
2
∇ ⋅ (ϕ\(\overline{f}\)) = ϕ(∇f) + \(\overline{f}\) ⋅ (∇ϕ)
3
∇ ⋅ (\(\overline{f}\) × \(\overline{g}\)) = \(\overline{g}\) ⋅ (∇ × \(\overline{f}\)) − \(\overline{f}\) ⋅ (∇ × \(\overline{g}\))
4
∇ × (∇ × \(\overline{f}\)) = ∇(∇ ⋅ \(\overline{f}\)) + ∇2\(\overline{f}\)
5
Not Attempted