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^-12 > 2.3*10^-8

To place the numbers in descending order, we need to compare their values.

First, let's rewrite each number in decimal form:

2.3 * 10^-10 = 0.00000000023
3.2 * 10^-10 = 0.00000000032
2.3 * 10^-12 = 0.00000000000023
2.3 * 10^-8 = 0.000000023

Now let's compare their values:

0.00000000023 < 0.00000000032, so 2.3 * 10^-10 comes before 3.2 * 10^-10.
0.00000000000023 < 0.00000000023, so 2.3 * 10^-12 comes before 2.3 * 10^-10.
0.00000000023 < 0.000000023, so 2.3 * 10^-12 comes before 2.3 * 10^-8.

Therefore, the numbers in descending order are:
3.2 * 10^-10
2.3 * 10^-10
2.3 * 10^-12
2.3 * 10^-8

To place the numbers in descending order, you need to compare the numerical values of the numbers without considering the exponents.

The given numbers are:
1) 2.3*10^-10
2) 3.2*10^-10
3) 2.3*10^-12
4) 2.3*10^-8

Let's remove the exponents and compare the values of the numbers:

1) 2.3*10^-10 = 0.00000000023
2) 3.2*10^-10 = 0.00000000032
3) 2.3*10^-12 = 0.00000000000023
4) 2.3*10^-8 = 0.000000023

Now, you can easily list them in descending order:

1) 3.2*10^-10 = 0.00000000032
2) 2.3*10^-8 = 0.000000023
3) 2.3*10^-10 = 0.00000000023
4) 2.3*10^-12 = 0.00000000000023

So, the numbers in descending order are:
3.2*10^-10, 2.3*10^-8, 2.3*10^-10, 2.3*10^-12