The weights of four different insects are given below.

Insect A: 2.19*10^-4 g;
Insect B: 5.00*10^-3 g;
Insect C: 9.0*10^-2 g;
Insect D: 1.50*10^-3 g

What is the order of these insects from heaviest to lightest?

Use 10^-4 as a common exponent. Then they are, as multiples of 10^-4:

2.19
50.0
900.0
15.0

Not too hard to order them now, eh?

To determine the order of the insects from heaviest to lightest, we will compare the weights of each insect.

Given weights:
Insect A: 2.19 * 10^-4 g
Insect B: 5.00 * 10^-3 g
Insect C: 9.0 * 10^-2 g
Insect D: 1.50 * 10^-3 g

First, let's convert the weights to a common unit, like grams, for easier comparison.

Insect A: 2.19 * 10^-4 g
Insect B: 5.00 * 10^-3 g
Insect C: 9.0 * 10^-2 g
Insect D: 1.50 * 10^-3 g

Converting using scientific notation:
Insect A: 0.000219 g
Insect B: 0.005 g
Insect C: 0.09 g
Insect D: 0.0015 g

Now, comparing the weights, we can determine the order:

Insect C (0.09 g)
Insect B (0.005 g)
Insect D (0.0015 g)
Insect A (0.000219 g)

So, the order of the insects from heaviest to lightest is: C, B, D, A.