Practice: Balance each of the chemical equations below. (Some equations may already be in balance.) In the space to the right, classify the reaction as a synthesis, decomposition, single replacement, or double replacement reaction. ___ AgNO3 + ___ KCl à ___ AgCl + ___ KNO3

___ H2O + ___ SO3 à ___ H2SO4

___ KI + ___ Cl2 à ___ KCl + ___ I2

___ NaHCO3 à ___ Na2CO3 + ___ H2O + ___ CO2

___ Zn + ___ HCl à ___ ZnCl2 + ___ H2

___ BaCl2 + ___ Na2SO4 à ___ BaSO4 + ___ NaCl

___ C3H8 + ___ O2 à ___ CO2 + ___ H2O

___ Al + ___ CuCl2 à ___ AlCl3 + ___ Cu

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.