Convert 2.5 g/mm2 to kg/m2 and check the dimensional correctness of T = 2pisqrt(m/(F/x)).

We know that $1 \text{ g} = 10^{-3} \text{ kg}$.

We know that $1 \text{ mm} = 10^{-3} \text{ m}$.
Therefore, $1 \text{ mm}^{-2} = (10^{-3} \text{ m})^{-2} = 10^6 \text{ m}^{-2}$.

The converted value is $\boxed{2.5 \times 10^3 \text{ kgm}^{-2}}$.

The LHS is $T$, which represents time period.
Dimension of LHS = $[T]$

$2\pi$ is a dimensionless constant.
Dimension of mass ($m$) = $[M]$
Dimension of force ($F$) = $[M][L][T^{-2}]$
Dimension of distance ($x$) = $[L]$

Dimension of $\frac{F}{x} = \frac{[M][L][T^{-2}]}{[L]} = [M][T^{-2}]$

Dimension of $\frac{m}{F/x} = \frac{[M]}{[M][T^{-2}]} = \frac{1}{[T^{-2}]} = [T^2]$

Dimension of $\sqrt{\frac{m}{F/x}} = \sqrt{[T^2]} = [T]$

Dimension of LHS = $[T]$
Dimension of RHS = Dimension of $2\pi \times$ Dimension of $\sqrt{\frac{m}{F/x}} = 1 \times [T] = [T]$
Since the dimension of LHS equals the dimension of RHS, the formula is dimensionally correct.
The formula is $\boxed{\text{dimensionally correct}}$.