Place the numbers in descending order.

2.3 × 10^−10 ; 3.2 × 10^−10 ; 2.3 × 10^−12 ; 2.3 × 10^−8

3.2 × 10^-10 ; 2.3 × 10^-10 ; 2.3 × 10^-8 ; 2.3 × 10^-12