For this question, assume that you have 1 compound. This compound is divided in half once, so you are left with 0.5. That 0.5 that remains is divided in half again, this is the second half-life, and you are left with 0.25. The final half life involves dividing 0.25 in half, which means you are left with 0.125. For the answer to make sense, you need to know your conversions between decimals and fractions. To make it simple, if you have 0.125 and you times it by 8, you are left with your initial value of 1. Therefore, after three half-lives, you are left with 1/8th of the compound.
Molecular mass of H2O is: 16+2*1=18
so moles of 40g of H2O is: 40/18=2.22
Answer:
H2O
Explanation:
There are 2 hydrogen atoms and 1 oxygen atom
The answer you are looking for is "bromine". Hope this helps!