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.
Answer:
C
Explanation:
the rain does help the soli it can make bacteria
The correct answer is C
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<u>Explanation:</u>
360-degree rotation of the planet in 24 hours causes a 12-hour time clock. The earth rotates on its own axis and around the sun.
It completes one rotation on its own axis in 24 hours equal to 360 degrees which make one complete solar day. The part of the earth which is exposed to the sun has daytime while the other part experiences the night time.
For this question, you must know that there are 6.022e23 atoms/molecules per mole of any substance (this is Avogadro's number). Therefore, your answer is 6.022e23 * 1.60 = 9.64e23 molecules of sulfur dioxide. (the "e" represents "times ten to the power of ___ ")
Answer:c
Explanation:
A valley will be carved out due to erosion.
