The answer to this question would be: 3.125%
Half-life is the time needed for a radioactive molecule to decay half of its mass. In this case, the strontium-89 is already gone past 5 half lives. Then, the percentage of the mass left after 5 half-lives should be:
100%*(1/2^5)= 100%/32=3..125%
Answer:

Explanation:
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In this case, considering that the by-mass percent of water is:

Given such percent and the mass of the sample, we can find the mass of water in grams in the sample by solving for it as shown below:

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a) The least number of decimal points is 0 so you should round the answer to 43.
b) The least number of significant figures is 2 so round to 7.3
c)The least number of decimal places is 1 so round to 225.7
d) The least number of significant figures is 3 so round to 92.0
e) The least number of significant figures is 3 so round to 32.4
f) The least number of decimal places is 0 so round to 104m^3
Basically, for addition and subtraction round to the least number of decimal places found in the factors, and for multiplication and division round to the least number of significant figures found in the factors.
Answer: (3) 15
Explanation: We criss-cross down the oxidation numbers to get the subscripts for the correct formulas. That means the X has an oxidation number of 5. The element with the + oxidation number is always written first so it is +5. Of the groups names, only group 15 has +5 as an oxidation number.
In 1 mole of
, there are 3 moles of ions, 1 mole of Ca^{2+} and 2 mole of
.

Molar mass of
is 110.98 g/mol. Calculating number of moles from given mass as follows:

Thus, number of moles of ions will be
.
Since, 1 mole of any substance has
units of that substance where
is Avogadro's number.
Thus, 9.38 mol of ions will have
number of ions.
Therefore, total number of ions in 347 g of
is
.