Considering a group of positive charges, which of the following...

As we know, net potential will be algebraic sum of potential due to each charge, so we can write ${V}_{net} = ∑ \left(\dfrac{k{Q}_{i}}{{r}_{i}}\right)$.

As given in the question, ${Q}_{i}$ and ${r}_{i}$ are positive, so

$∴ {V}_{net} > 0$

But electric field is a vector quantity, so it can be zero for a given arrangement of charges. For example, electric field at the centre of the two equal charges at certain distance will be zero as electric field due to both charges will be in opposite direction and hence will cancel each other.