Step 2: Now that you have counted the atoms on each side, add coefficients to balance the equation. Check your work by updating the number of atoms on each side in the table below (Remember to multiply coefficients by subscripts): NaF + NaBr + CaF2 CaBr2 Reactants Products Na- Na- Br- Br- Ca- Ca- IF- ​

Ithink about 50 % of an original isotope's number of atoms remain

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.

Vander waals forces are inter molecular bonds that exist within molecules of the same substance. a water molecule is made up of oxygen and hydrogen atoms which share electrons between each other. the vander waals forces are forces that exist between multitude of different  molecules of water. dipole dipole forces is the type of vander waals force that exist in water. the oxygen atom which is more electronegative pulls the shared electron closer to itself thus generating a partial negative charge while the hydrogen acquire a partial positive charge. these two different charges causes attraction to occur in water molecules.

Elements would be the right answer