Calculate the amount, in grams, of an original 300 gram sample of potassium 40 remaining after 3.9 billion years. a. 300
b. 150
c. 75
d. 37.5​

What is the mass of the same rock on the earth

Two forces produce equal torques on a door about the door hinge. the first force is applied at the midpoint of the door; the second force is applied at the doorknob. both forces are applied perpendicular to the door. which force has a greater magnitude?

Which missing item would complete this alpha decay reaction ? > 228/88ra + 4/2he a.224/96 rn b. 232/90 th c. 230/92 u d. 235/92 u