Which of the following steps should be used when applying hess law?

There are actually 5 skills in applying Hess’ Law. According to science.uwaterloo and chem.libretexts.org these are the 5 skills.

- changing the enthalpy of the reaction whenever the equation changes

- interpreting the Hess’ Law

- applying the principle of conservation of energy to solve the problem

- sketching an energy diagram for any related reactions

- and lastly using the diagram to explain the Hess’ Law.

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.