Option 3 using forest land to build homes
The number of grams of radon 222 did it have 15.2 ago was 49.6 grams( answer C)
<u>calculation</u>
- calculate the number of half life it has covered from 15.2 days to 3.8 days
that is divide 15.2/ 3.8 = 4 half life
- half life is time taken for a radio activity of a specified isotope to fall to half its original mass
therefore 3.8 days ago it was 3.1 x2 = 6.2 grams
7.6 days ago it was 6.2 x2 = 12.4 grams
11.4 days ago it was 12.4 x2= 24.8 grams
15.2 days ago it was 24.8 x2=49.6 grams
Surface tension under water results from greater attraction of liquid molecules to each other, due to a process called cohesion, than to molecules in the air, due to a process called adhesion.
<span>Avogadro's number.
1 mole of any substance, molecule or element is equal to a certain amount of atom.
6.022 x 10^23 is the Avogradro's constant.
Magnesium Oxide is a compound. therefore if you have 30.3 g of it (1 mol), it will have the same number of atoms.
34.69 moles of MgO has 208.9 x 10^23 number of atoms.
2.089 x 10^25 is also a correct answer.</span><span>
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<span>I bet this is the notation used in nuclear reactions. The superscript represents the mass number while the subscript represents the atomic number of the element X. So, we find the element with an atomic number of 12. That would be Magnesium or Mg.</span>