An organism had 1,000 grams of carbon-14 (a radioactive form of carbon) in it when it died. how much remains after five half-lives?

After 5th half life the remaining mass is 31.25 g.

Explanation:

Given data:

Total mass of carbon-14 = 1000 g

Mass remain after 5 half lives = ?

Solution:

At time zero = 1000 g

At first half life = 1000 g/2 = 500 g

At second half life =  500 g/ 2= 250 g

At third half life = 250 g/ 2 = 125 g

At 4th half life = 125 g/2 = 62.5 g

At 5th half life = 62.5 g/2 = 31.25 g

Thus after 5th half life the remaining mass is 31.25 g.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.