Answer:
Answer : The number of atoms present in 159 g of calcium are
Explanation :
First we have to calculate the moles of calcium.
Molar mass of calcium = 40 g/mole
Now we have to calculate the number of atoms of calcium.
As, 1 mole of calcium contains number of atoms of calcium
So, 3.975 mole of calcium contains number of atoms of calcium
Therefore, the number of atoms present in 159 g of calcium are
Explanation:
Answer: it consists of two simple machines: a lever and a wheel and axle. Effort is applied to the lever by picking up the handles of the wheelbarrow.
Explanation:
Answer:
plzz mark brainliast:
Explanation:
clue: The reaction has a single reactant.
rxns is an abbreviation for reactions
Answer:
288 grams
Explanation:
The amount of any radiative substance left after some time is calculated by
amount left = 
where x is the initial amount of substance
n is the number of half lives
one half live is the time in which amount of substance reduce to half of its initial value.
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amount left = 4.5 grams
half life of iodine-125 = 60 days
total time in which substance reduced to 4.5 grams = 360 days
thus,
number of half life in 60 days = 360/60 = 6
thus, there are period of 6 half lives
in each half life the amount of substance reduces to its previous half
let the initial amount be x grams
using the formula
amount left = 

Thus, 288 grams was the initial amount of iodine-125