Suppose you find a rock that contains some potassium-40 ...

[CBme]

Suppose you find a rock that contains some potassium-40 (half-life of 1.3 billion years). You measure the amount and determine that there are 5 grams of potassium-40 in the rock.
 
  By measuring the amount of its decay product (argon-40 ) present in the rock, you realize that there must have been 40 grams of potassium-40 when the rock solidified. How old is the rock? A) 1.3 billion years
  B) 2.6 billion years
  C) 3.9 billion years
  D) 5.2 billion years
  E) none of the above

Question 2

What are the Aten asteroids?
 
  What will be an ideal response?

[vickyvicksss]

Answer to Question 1

C

Answer to Question 2

Asteroids staying very close to the Sun, with semimajor axes less than 1 A.U. and periods of less than a year. Most of the ones now known do have aphelions slightly outside our orbit.

[CBme]

Thanks for the timely response, appreciate it

[upturnedfurball]

Wow, this really help