Potassium-40 decays to argon-40 with a half-life of 1.27 109 yr. ...

[scienceeasy]

Potassium-40 decays to argon-40 with a half-life of 1.27  109 yr. The age of a mineral sample that has a mass ratio of 40Ar to 40K of 0.330 is ________ yr.
 
  A) 3.85  109
  B) 1.77  109
  C) 2.55  109
  D) 3.62  108
  E) 5.23  108

Question 2

Which point on the cooling curve corresponds to the freezing point of paradichlorobenzene?
 
  A) the lowest point on the curve
  B) the highest point on the curve
  C) the flat portion of the curve
  D) the midpoint of the curve
  E) the final point on the curve

[prumorgan]

Answer to Question 1

E

Answer to Question 2

C)

[scienceeasy]

Gracias!

[AmberC1996]

TYSM