Answer:
after 45 days 9 g left
Explanation:
Given data:
Half life Na-24 = 15 days
Mass of sample = 72 g
Mass remain after 45 days = ?
Solution:
Number of half lives passed:
Number of half lives = time elapsed / half life
Number of half lives = 45 days / 15 days
Number of half lives = 3
At time zero total amount = 72 g
After first half life = 72 g/ 2= 36 g
At 2nd half life = 36 g/2 = 18 g
At 3rd half life = 18 g/2 = 9 g
Thus after 45 days 9 g left.
I'm pretty sure it is the 2nd one.
Answer:
Water moves from the ground or oceans into the atmosphere through a process called evaporation. It's a process that happens on a molecular level when the molecules of water are really energized and rise into the air. Now you've got water in the air and water on land. Organisms all over the Earth need water to survive.
Explanation:
It’s ionic
KCl(at)
Potassium chloride
