<span>The mass of Cl on the periodic table is 35.45 atomic mass units. This is an average mass of the isotopes of chlorine. Most Cl atoms in nature have a relative mass of about 35 atomic mass units. Most of the remaining Cl isotopes have a relative mass of 37 atomic mass units.
</span><span>The number 35.45u is the result of the natural mixture of Cl-35 and Cl-37, which produces the observed </span><span>value. </span>
Research the July Monarchy, and the beggining of the Second Republic. That should help out.
<span>A Helium nucleus is likely to be unstable if it has no neutrons because the remaining protons will repel electromagnetically and basically cause the atom to fall apart. The neutrons could have helped in holding everything together, and not make the protons repel.</span>
PH is your answer
Hope this helps!!
Half life of a radio-active material is refereed to the time required for reducing its activity to 50 %.
Now, when I-131 passes 1st half life, it's activity will reduce to half i.e. 50%
When, I-131 passes 2nd half life, activity of I-131 will be reduced to 25%
On passing, 3rd half-life, percent activity of the I-131 <span>remaining will be 12.5 %.</span>
