Answer:
7.5 gm left
Explanation:
Bismuth-210 has a half life of 5 days
15 days is 15/5 = 3 half lives
since half the amount is left in 5 days or 1 half life
(1/2) x (1/2) x (1/2) the staring amount would be left in
3 half lives. so 1/8 is left
(1/8) x 60.0 = 7.5 gm left

<u>Difference </u><u>between </u><u>Atomic </u><u>mass</u><u>, </u><u>relative </u><u>atomic </u><u>mass </u><u>and </u><u>average </u><u>atomic </u><u>mass</u><u> </u><u>:</u><u>-</u>
<h3><u>Atomic </u><u>Mass </u><u>:</u><u>-</u></h3>
- Atomic mass is the mass of neutrons and protons present in the nucleus of an atom .
- It is always calculated for a single element and having direct value
- For isotopes also, the atomic mass is calculated separately . Example :- <u>Carbon </u><u>1</u><u>2</u><u> </u><u>,</u><u> </u><u>carbon </u><u>1</u><u>3</u><u> </u><u>and </u><u>carbon </u><u>1</u><u>4</u><u> </u><u>have </u><u>different </u><u>atomic </u><u>mass</u><u>. </u>
- The SI unit of Atomic mass is " u" and "amu"
<h3>
<u>Relative </u><u>Atomic </u><u>mass </u><u>:</u><u>-</u></h3>
- Relative atomic mass is mean mass of the atoms of an element which is compared to the 1/12th mass of carbon - 12 .
- Carbon - 12 is taken as a relative when we calculate the relative atomic mass of any element
- For calculating relative atomic mass, we need to know the masses, percentage and abundance of all types of elements
- Relative atomic mass is a dimension less quantity
<h3><u>Average </u><u>Atomic </u><u>Mass </u><u>:</u><u>-</u></h3>
- Average atomic mass is the average mass of an atoms of a particular element by considering it's isotopes
- While we calculate average atomic mass is a standardized number. Whereas, Average atomic mass sometimes varies geologically .
- It also includes percentage, abundance and masses of given element .
- In average atomic mass, We do not compare mean value with the 1/12 mass of carbon - 12
- The unit of Average atomic mass is "Amu" or " u " .
Hello, to answer your question. It is because all machines require a fuel or source to power it making it imperfect for using some source that may not be renewable.
Signed by, Virtouso Sargedog
E.g. in H3PO4 (O, -2).
8. The sum of the oxidation states of all the atoms in a species must be equal to net charge on the species. e.g. Net Charge of HClO4 = 0, i.e. [+1(H)+7(Cl)-2<span>*4(O)] = 0.</span>