Select the correct answer. chicxulub is a crater on the yucatán peninsula of mexico. it was formed 6.5 × 107 years ago. vredefort crater in south africa was formed approximately 2 × 109 years ago. sudbury basin in canada is a crater that formed approximately 1.8 × 109 years ago. acraman crater in australia was formed 5.8 × 108 years ago. which crater is the oldest? a. chicxulub crater b. vredefort crater c. acraman crater d. sudbury basin

The oldest crater is the one with the greatest age. The ages are given in scientific notation. Effectively, we're asked to find the largest of the four numbers ...

6.5×10^7
2×10^9
1.9×10^9
5.8×10^8

__

exponents

Numbers in scientific notation are compared by first comparing the exponents of the powers of 10. The larger exponent signifies the larger number. Here, we have two numbers with the largest exponent:

2×10^9
1.8×10^9

mantissas

When the exponents are the same, the largest number is the one with the largest mantissa:

2 > 1.8 ⇒ 2×10^9 > 1.8×10^9

The oldest crater, with the age of 2×10^9 years, is the Vredefort Crater.